fix: frappe.clear_cache should drop all keys (backport #22156)

[mergify]

We are dropping some keys which are hardcoded in function.

• this over time might be out of sync with rest of the code.
• other apps cache stuff too.

Best fix: just clear everything.

---

This is an automatic backport of pull request #22156 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 04a13ca has failed:

On branch mergify/bp/version-14-hotfix/pr-22156
Your branch is up to date with 'origin/version-14-hotfix'.

You are currently cherry-picking commit 04a13ca97c.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   frappe/__init__.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   frappe/tests/test_caching.py

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally