fix(tests): Fix false negative cram tests

[corneliusroemer]

Description of proposed changes

• Fix #1665 by properly escaping square brackets
• Add a warning to diff_jsons.py when exclude-regex-path is used incorrectly like in issue 1665 to prevent this issue from reoccurring silently
• Broaden default exclude-paths to now be ["root['generated_by']", "root['meta']['updated']"] instead of ["root['generated_by']['version']"]. This allows simplification of a lot of invocations of diff_jsons.py and in turn reduces chance of errors similar to issue 1665. Anything within generated_by can be ignored by cram tests, meta.updated is only used in export, but no harm excluding by default as it isn't used in any other tests. If there's opposition, happy to revert that change.
• Make the tests pass that should have failed but weren't failing due to issue 1665, by updating the test files. @jameshadfield or @huddlej should check that the behaviour is as intended, but the changes seems small and reasonable so I'm not too worried. Update: @jameshadfield confirmed that the tests didn't mask any unintended behavior.

Checklist

• [x] Automated checks pass
• [x] Check if you need to add a changelog message
• [x] Check if you need to add tests
• [x] Check if you need to update docs

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 72.29%. Comparing base (29188d4) to head (27d18b4). Report is 4 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1666 +/- ## ========================================== + Coverage 72.26% 72.29% +0.02% ========================================== Files 79 79 Lines 8272 8276 +4 Branches 1691 1691 ========================================== + Hits 5978 5983 +5 + Misses 2009 2008 -1 Partials 285 285 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[corneliusroemer]

This might be worth an internal changelog entry