Partial Event Building: Update configuration and add unit tests

Changes introducing extensive unit testing of partial event building configuration in TriggerMenuMT (ATR-22242).

1. Replace derived config classes in TrigPartialEventBuildingConfig with config functions returning a tool instance (required for the unit test from point 3 below to work correctly).
2. Extend menu_config_tests.py with a new consistency check of partial event building configuration.
3. Add a unit test for the EventBuildingSequenceSetup module testing the configuration of PEB writer tools.
4. Fix stream misconfiguration uncovered by the test added in point 2. The "CSCPEB" chain was streamed to a full-event-building stream "CSC". That stream should not be full-event-building.