Optimize tests for lower CI runtime

[AaronFeickert]

Tests currently take around 10 minutes to complete via CI. We should do a comprehensive review to see if there are any that can be optimized, refactored, or removed to keep CI speedy for quicker workflows.

[AaronFeickert]

This is now down to 4 minutes, which is not bad! I'll keep this issue open anyway, since a comprehensive review of test coverage is still useful.