gh-142752: add more thread safety tests for mock

[kumaraditya303]

• Issue: Thread safety of Mock and ThreadingMock #142752

[miss-islington-app]

Thanks @kumaraditya303 for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-142856 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-142857 is a backport of this pull request to the 3.13 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot x86-64 MacOS Intel NoGIL 3.14 (tier-2) has failed when building commit 4feba4d.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1679/builds/744) and take a look at the build logs.
4. Check if the failure is related to this commit (4feba4d) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1679/builds/744

Failed tests:

• test_capi

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "<string>", line 10, in <module>
  File "<frozen importlib._bootstrap>", line 816, in module_from_spec
  File "<frozen importlib._bootstrap_external>", line 1053, in create_module
  File "<frozen importlib._bootstrap>", line 491, in _call_with_frames_removed
ImportError: module _test_module_state_shared does not support loading in subinterpreters
xpected failure