Remove test samples (#11906)

I don't know that these have caught any real issues in the last couple
years, however, the standard library ones have been a bit of a pain,
most recently in #11905.

Jukka was okay removing the stdlib samples two years ago, see
#8838 (comment)
We now have tooling like mypy primer that runs mypy over a much larger
and more varied corpus of code on every PR.

The other samples haven't caused me much bother (except for crawl,
which I removed in #9375), but except for crawl2, they're all very simple.
I don't think they provide us much value, unless they have sentimental or
historical value.

Author: hauntsaninja

LICENSE

@@ -26,8 +26,8 @@ DEALINGS IN THE SOFTWARE.
 
 = = = = =
 
-Portions of mypy and mypyc are licensed under different licenses.  The
-files under stdlib-samples as well as the files
+Portions of mypy and mypyc are licensed under different licenses.
+The files
 mypyc/lib-rt/pythonsupport.h, mypyc/lib-rt/getargs.c and
 mypyc/lib-rt/getargsfast.c are licensed under the PSF 2 License, reproduced
 below.