Fix GNNHS VertexDecoratorAlg failure (ATLASRECTS-8178)

Following !78633 (merged), the sumPt vertex decoration can get properly locked by the PhotonVertexSelection, creating a crash when running the VertexDecoratorAlg which attempts to modify it.

In practice, this was already fixed in main with !77093 (merged)

Sweeping therefore some relevant commits from main to 24.0 to avoid the failure of the GNNHS unit test:

• !77025 (merged)
• !77093 (merged)

Removes also some unnecessary SG::AuxElement::Decorator

The commits should not be squashed to preserve history and facilitate the sweep in main

Closes ATLASRECTS-8178

FYI @jburzyns @gfrattar @ssnyder

added full-unit-tests label

This merge request affects 1 package:

• InnerDetector/InDetRecTools/InDetGNNHardScatterSelection

This merge request affects 2 files:

• InnerDetector/InDetRecTools/InDetGNNHardScatterSelection/src/VertexDecoratorAlg.cxx
• InnerDetector/InDetRecTools/InDetGNNHardScatterSelection/src/VertexDecoratorAlg.h

Adding @goetz ,@sroe as watchers

added 24.0 InnerDetector review-pending-level-1 labels

added urgent label

CI Result SUCCESS (hash ce71f1cf)

	Athena
externals
cmake
make
tests

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Changes are fine and CI succeeds, approving for L1. -L1

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

added review-approved-tier0 label

mentioned in commit 42a76b8a

merged

mentioned in merge request !78769 (merged)