Remove Change Type template and change label names

[ognyanstoimenov]

Reference Issues/PRs

What does this implement or fix?

• Remove template and only rely on manually adding labels with the CI checks failing if none are provided. As discussed here https://github.com/man-group/ArcticDB/pull/2174/files#r1962142382
• Add label names to the existing ones that are used for changelog generation:
  • major or api break
  • minor or enhancement
  • patch or bug
• Fix permissions for automatic branch creation
• Fix changelog builder not ignoring rc releases when comparing to previous release.
• Enforced branch protection for the release branch so it is only creatable by admins (and the workflow user's special token) https://github.com/man-group/ArcticDB/settings/rules/3823486
• Fix docs build (remove unsupported option)

Any other comments?

Checklist

Checklist for code changes...

• Have you updated the relevant docstrings, documentation and copyright notice?
• Is this contribution tested against all ArcticDB's features?
• Do all exceptions introduced raise appropriate error messages?
• Are API changes highlighted in the PR description?
• Is the PR labelled as enhancement or bug so it appears in autogenerated release notes?

[G-D-Petrov]

LGTM