Cleanup AI Chat tests after cutoff

Summary

Update AI chat specs to accommodate addon cut o... (#442816 - closed) changed our tests so they accommodated cutoff logic, however, they should work before cutoff as well, that's why we can't properly clean them up and remove outdated parts from the setup.

We need to review the test setup and clean it after the cut off, as well as remove outdated test scenarios.

In another case, we don't use the standard setup and this should be revised as well.

Business objective

Tests are our first line of defence against bugs and regressions. Having cleaner test setup increases dev confidence in work and ensure that in case of emergency code could be updated much quicker. Also, it improves velocity of feature development. Leaving tests not cleaned up might result in costly master-broken situations or dragging of development of important features.