BUG: setup timezone in deploy

Summary

• Refactor and test UTCTimeZoneShift class.
• Make the timezone changeable during runtime in debug mode for integration testing.
• The actual bug was in caosdb-deploy https://gitlab.indiscale.com/caosdb/src/caosdb-deploy/-/merge_requests/177. These changes are just for testability.

Test Environment

No manual testing, pipeline is sufficient.

• Test in caosdb-pyinttest!43 (merged)
• Pylib refactoring in caosdb-pylib!65 (merged)

Check List for the Author

• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

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