Consider removing sqlalchemy-utils dependency

[sphuber]

In PR #4855 the sqlalchemy-utils dependency was updated such that it would be compatible with sqlalchemy>=1.4. This took a significant amount of time and even required removing one of the utility functions that was being used and copying the original implementation before it was changed in the updated version. After that PR, only few uses remain of the library and so the question is raised whether it doesn't make sense to simply get rid of the dependency entirely.