Add prescale set for HLT reprocessings to:
- remove triggers for P1 that are not useful for reprocessings
- apply a PS of 10 to low-mu MB chains that use a lot of CPU in high-mu pp (ATR-25459)
Sets these also for all the PhysicsP1 tests (TrigP1Test) that process events.
Also removes prescale set from menu name determining L1 menu mapping.