Adding a simple sequence scanner in HLT/CF

This is a requested task in ATR-19600. Basically, after the CF tree is created, but before running, this functions identifies cases in which a sequence is instantiated multiple times in different steps, which likely creates a stall. More checks can be added

This merge request affects 2 packages:

• Trigger/TrigSteer/DecisionHandling
• Trigger/TriggerCommon/TriggerMenuMT

Adding @tamartin ,@bernius as watchers

added Trigger TriggerMenu master review-pending-level-1 labels

Nice this happened recently on !35672 (merged) and was not immediately obvious what the cause was.

Thanks, indeed I can confirm I see this error with the changes from !35672 (merged), so this works as expected

2020-09-09 17:57:06,585  Py:TriggerMenuMT.HLTMenuConfig.Menu.HLTCFConfig   ERROR sequenceScanner: Sequence pebSequence_LArPEB is expected in more than one step: {'5', '4'}

great, happy it’s helpful !

CI Result SUCCESS (hash 7da89077)

	Athena	AthSimulation	AthGeneration	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 19860]

All looks fine, approving. Cheers, L1

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 720e1716

added sweep:ignore label