test(e2e): adjust trashbin tests to be less flaky

[susnux]

Summary

1. Move general files delete action (thats not trashbin app!) to files tests.
2. Delete files (move to trashbin) before loading the page so previews are not generated so they cannot lock the file.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[come-nc]

👍

[kesselb]

🐘

[come-nc]

@susnux Are backports needed? Suppose at least stable31?

[susnux]

/backport to stable31

[susnux]

/backport to stable30

[backportbot]

The backport to stable30 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable30
git pull origin stable30

# Create the new backport branch
git checkout -b backport/51211/stable30

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 0ed7e403

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/51211/stable30

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[skjnldsv]

/backport to stable29

[backportbot]

The backport to stable29 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable29
git pull origin stable29

# Create the new backport branch
git checkout -b backport/51211/stable29

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 0ed7e403

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/51211/stable29

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.