Fix the HLT TimeBurner chain and prevent accepting events with unknown stream type

Fix the issue where HLT TimeBurner chain was accepting all events (to the stream unknown_DISCARD) while it should be rejecting all. In addition, prevent such issues from happening by printing an error and returning failure in HLT output building if an event is accepted to any stream with unknown type. This way an issue like this can be discovered in CI before its merged.

Changes (two separate commits):

1. HLTResultMTByteStreamCnv: Fail if an event is accepted to stream with unknown type. cc @wiedenma
2. TriggerMenuMT+TrigGenericAlgs: Remove comboHypoCfg=None from step definition and create a reject decision object in TimeBurner::execute. cc @tamartin

Closes ATR-22775