[ATR-22359] Create empty bunchgroup structure until the real one is ready to be filled

Resolves issue located in [ATR-22335]

The real data will be filled when the BG JSON is available.

This merge request affects 1 file:

• Trigger/TrigConfiguration/TrigConfxAOD/Root/prepareTriggerMenu.cxx

Adding @mark ,@orlando ,@cmorenom ,@asonay as watchers

added Trigger master review-pending-level-1 labels

CI Result SUCCESS (hash 2344a1a7)

	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 23291]

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

merged

mentioned in commit a07c379e

added sweep:ignore label