MetaReader: Rather than dummy defaults just do not propagate missing metadata entries

Rather than dummy defaults just do not propagate missing metadata entries in MetaReader.

/cc @jchapman @maszyman @tsulaia

added full-unit-tests label

This merge request affects 1 package:

• Tools/PyUtils

This merge request affects 1 file:

• Tools/PyUtils/python/MetaReader.py

added Tools analysis-review-required main review-pending-level-1 labels

CI Result SUCCESS (hash 35c60c0a)

	Athena	AthSimulation	AthGeneration	AnalysisBase	AthAnalysis
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
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
AthAnalysis: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-EL9 9531] (remote access info)

Looks good, approving --L1

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

I suspect this won't affect analysis code. Approving for AR.

Nils [Analysis RC]

added analysis-review-approved label and removed analysis-review-required label

merged

mentioned in commit 860768bd