chore: drop support for old forest versions

[LesnyRumcajs]

Summary of changes

Changes introduced in this pull request:

• The version 0.12.0 is from 2023, which is ages in our world, so there's no point in supporting it anymore. Moved the pole to July 2024.
• Removed workarounds we had for 0.12.0 and related migrations.
• Removed a redundant car_db migration test.
• Revamped the existing failing migration test, given we no longer have failing migrations (I guess the only existing one is missing some assertions...) at the migration phase.
• This decreases the duration of the DB migration job.

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.