Refactor of CI

[labkode]

This PR:

• refactors the test suite into more granular chunks
• temporary disables some tests that will need to be fixed later on (Debug and re-enable some tests #4841)
• permanently removes ownCloud tests
• bumps deps to latest
• fix many tests to not rely on internal data structures

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.