tox: skip install stages are not skipping install

[jmahlik]

Describe the bug
Some tox stages can skip the install of the entire testing stack. The current config is resulting in these stages installing the .[test] extra, so they are taking a lot longer than they should. Fixing should improve ci time significantly for the PR checks.

Flake8 for instance takes about 1/7 if the time.

Current config -- results in .[test] being installed.

[testenv:flake8]
skipdist = true
skip_install = true
commands =
    pip install --exists-action=w -r requirements/tox/flake8_requirements.txt
    flake8

After -- only installs the flake8 deps

[testenv:flake8]
skipdist = true
skip_install = true
deps =
    -r requirements/tox/flake8_requirements.txt
commands =
    flake8

Timings for an environment recreation. These timings are on windows, so they're a quite inflated. The relative time is important though. This is with everything in the local pip cache.

Notice the large amount of deps installed before the change

Before Change

time tox -e flake8 -r
flake8 recreate: \.tox\flake8
flake8 installdeps: .[test]
flake8 installed: accelerate==0.27.0,aiohttp==3.9.5,aiosignal==1.3.1,alembic==1.13.1,anyio==4.3.0,apache-airflow==2.8.4,apache-airflow-providers-amazon==7.2.1,apache-airflow-providers-common-io==1.3.1,apache-airflow-providers-common-sql==1.12.0,apache-airflow-providers-ftp==3.8.0,apache-airflow-providers-http==4.10.1,apache-airflow-providers-imap==3.5.0,apache-airflow-providers-smtp==1.6.1,apache-airflow-providers-sqlite==3.7.1,apispec==6.6.0,argcomplete==3.3.0,asgiref==3.8.1,asn1crypto==1.5.1,asttokens==2.4.1,atomicwrites==1.4.1,attrs==23.2.0,awslogs==0.14.0,Babel==2.14.0,bcrypt==4.1.2,beautifulsoup4==4.12.3,black==24.3.0,blinker==1.7.0,boto3==1.34.85,botocore==1.34.85,Brotli==1.1.0,cachelib==0.9.0,certifi==2024.2.2,cffi==1.16.0,charset-normalizer==3.3.2,click==8.1.7,clickclick==20.10.2,cloudpickle==2.2.1,colorama==0.4.6,colorlog==4.8.0,ConfigUpdater==3.2,connexion==2.14.2,contextlib2==21.6.0,coverage==6.1.2,cron-descriptor==1.4.3,croniter==2.0.3,cryptography==42.0.5,decorator==5.1.1,Deprecated==1.2.14,dill==0.3.8,distlib==0.3.8,dnspython==2.6.1,docker==6.1.3,docutils==0.21.1,email-validator==1.3.1,execnet==2.1.1,executing==2.0.1,fabric==2.6.0,fastjsonschema==2.19.1,filelock==3.13.4,flake8==4.0.1,Flask==2.2.5,Flask-AppBuilder==4.3.11,Flask-Babel==2.0.0,Flask-Caching==2.1.0,Flask-JWT-Extended==4.6.0,Flask-Limiter==3.5.1,Flask-Login==0.6.3,Flask-Session==0.5.0,Flask-SQLAlchemy==2.5.1,Flask-WTF==1.2.1,frozenlist==1.4.1,fsspec==2024.3.1,gevent==24.2.1,geventhttpclient==2.0.2,google-pasta==0.2.0,google-re2==1.1,googleapis-common-protos==1.63.0,greenlet==3.0.3,grpcio==1.62.1,gunicorn==22.0.0,h11==0.14.0,httpcore==1.0.5,httpx==0.27.0,huggingface-hub==0.22.2,idna==3.7,importlib-metadata==6.11.0,importlib_resources==6.4.0,inflection==0.5.1,iniconfig==2.0.0,invoke==1.7.3,ipython==8.23.0,itsdangerous==2.2.0,jedi==0.19.1,Jinja2==3.1.3,jmespath==0.10.0,joblib==1.4.0,json5==0.9.25,jsonpath-ng==1.6.1,jsonpickle==3.0.4,jsonschema==4.21.1,jsonschema-specifications==2023.12.1,jupyter_core==5.7.2,lazy-object-proxy==1.10.0,limits==3.10.1,linkify-it-py==2.0.3,lockfile==0.12.2,lxml==5.2.1,Mako==1.3.3,markdown-it-py==3.0.0,MarkupSafe==2.1.5,marshmallow==3.21.1,marshmallow-oneofschema==3.1.1,marshmallow-sqlalchemy==0.26.1,matplotlib-inline==0.1.7,mccabe==0.6.1,mdit-py-plugins==0.4.0,mdurl==0.1.2,mock==4.0.3,more-itertools==10.2.0,mpmath==1.3.0,multidict==6.0.5,multiprocess==0.70.16,mypy-boto3-appflow==1.34.0,mypy-boto3-rds==1.34.83,mypy-boto3-redshift-data==1.34.0,mypy-extensions==1.0.0,nbformat==5.10.4,networkx==3.3,numpy==1.26.4,onnx==1.16.0,opentelemetry-api==1.24.0,opentelemetry-exporter-otlp==1.24.0,opentelemetry-exporter-otlp-proto-common==1.24.0,opentelemetry-exporter-otlp-proto-grpc==1.24.0,opentelemetry-exporter-otlp-proto-http==1.24.0,opentelemetry-proto==1.24.0,opentelemetry-sdk==1.24.0,opentelemetry-semantic-conventions==0.45b0,ordered-set==4.1.0,packaging==24.0,pandas==1.4.4,paramiko==3.4.0,parso==0.8.4,pathlib2==2.3.7.post1,pathos==0.3.2,pathspec==0.12.1,pendulum==3.0.0,pillow==10.3.0,platformdirs==4.2.0,pluggy==1.4.0,ply==3.11,pox==0.3.4,ppft==1.7.6.8,prison==0.2.1,prompt-toolkit==3.0.43,protobuf==4.25.3,psutil==5.9.8,pure-eval==0.2.2,py==1.11.0,py4j==0.10.9.5,pycodestyle==2.8.0,pycparser==2.22,pyflakes==2.4.0,Pygments==2.17.2,PyJWT==2.8.0,PyNaCl==1.5.0,pyspark==3.3.1,pytest==6.2.5,pytest-cov==3.0.0,pytest-forked==1.6.0,pytest-rerunfailures==10.2,pytest-timeout==2.1.0,pytest-xdist==2.4.0,python-daemon==3.0.1,python-dateutil==2.9.0.post0,python-nvd3==0.15.0,python-rapidjson==1.16,python-slugify==8.0.4,pytz==2024.1,pyvis==0.2.1,pywin32==306,PyYAML==6.0,redshift-connector==2.1.1,referencing==0.34.0,requests==2.31.0,requests-toolbelt==1.0.0,rfc3339-validator==0.1.4,rich==13.7.1,rich-argparse==1.4.0,rpds-py==0.18.0,s3transfer==0.10.1,safetensors==0.4.3,sagemaker @ file:///sagemaker-python-sdk,sagemaker-experiments==0.1.35,sagemaker-schema-inference-artifacts==0.0.5,sagemaker_feature_store_pyspark_3.3==1.1.2,schema==0.7.5,scikit-learn==1.3.0,scipy==1.10.1,scramp==1.4.5,setproctitle==1.3.3,six==1.16.0,smdebug-rulesconfig==1.0.1,sniffio==1.3.1,soupsieve==2.5,SQLAlchemy==1.4.52,SQLAlchemy-JSONField==1.0.2,sqlalchemy-redshift==0.8.14,SQLAlchemy-Utils==0.41.2,sqlparse==0.5.0,stack-data==0.6.3,stopit==1.1.2,sympy==1.12,tabulate==0.9.0,tblib==3.0.0,tenacity==8.2.3,termcolor==2.4.0,text-unidecode==1.3,threadpoolctl==3.4.0,time-machine==2.14.1,toml==0.10.2,tomli==2.0.1,torch==2.2.2,tox==3.24.5,tqdm==4.66.2,traitlets==5.14.2,tritonclient==2.36.0,typing_extensions==4.11.0,tzdata==2024.1,uc-micro-py==1.0.3,unicodecsv==0.14.1,universal-pathlib==0.1.4,urllib3==2.2.1,virtualenv==20.25.3,watchtower==2.0.1,wcwidth==0.2.13,websocket-client==1.7.0,Werkzeug==2.2.3,wrapt==1.16.0,WTForms==3.1.2,xgboost==1.7.6,yarl==1.9.4,zipp==3.18.1,zope.event==5.0,zope.interface==6.3
flake8 run-test-pre: PYTHONHASHSEED='42'
flake8 run-test: commands[0] | pip install --exists-action=w -r requirements/tox/flake8_requirements.txt
Requirement already satisfied: flake8==4.0.1 in \.tox\flake8\lib\site-packages (from -r requirements/tox/flake8_requirements.txt (line 1)) (4.0.1)
port-0.4.6-py2.py3-none-any.whl (10 kB)
Requirement already satisfied: mccabe<0.7.0,>=0.6.0 in .tox\flake8\lib\site-packages (from flake8==4.0.1->-r requirements/tox/flake8_requirements.txt (line 1)) (0.6.1)
Requirement already satisfied: pycodestyle<2.9.0,>=2.8.0 in .tox\flake8\lib\site-packages (from flake8==4.0.1->-r requirements/tox/flake8_requirements.txt (line 1)) (2.8.0)
Requirement already satisfied: pyflakes<2.5.0,>=2.4.0 in .tox\flake8\lib\site-packages (from flake8==4.0.1->-r requirements/tox/flake8_requirements.txt (line 1)) (2.4.0)
Installing collected packages: flake8-future-import
Successfully installed flake8-future-import-0.4.6
flake8 run-test: commands[1] | flake8

real    7m1.687s
user    0m0.000s
sys     0m0.109s

Post change

time tox -e flake8 -r
flake8 recreate: .tox\flake8
flake8 installdeps: -rrequirements/tox/flake8_requirements.txt
flake8 installed: flake8==4.0.1,flake8-future-import==0.4.6,mccabe==0.6.1,pycodestyle==2.8.0,pyflakes==2.4.0
flake8 run-test-pre: PYTHONHASHSEED='42'
flake8 run-test: commands[0] | flake8

real    0m52.988s
user    0m0.000s
sys     0m0.046s

To reproduce
Run the tox linting stages. On windows, it takes a few hours just making environments which is how I noticed this.

Expected behavior
Only install the needed deps

Screenshots or logs
n/a

System information
A description of your system. Please provide:

• SageMaker Python SDK version: master
• Framework name (eg. PyTorch) or algorithm (eg. KMeans): n/a
• Framework version: n/a
• Python version: n/a
• CPU or GPU: n/a
• Custom Docker image (Y/N): n/a

Additional context
I can submit a PR with changes.