egammaPerformance: Fix cppcheck warnings.

Prefer to initialize class members in an initialization list.

This merge request affects 1 package:

• Reconstruction/egamma/egammaPerformance

This merge request affects 1 file:

• Reconstruction/egamma/egammaPerformance/src/egammaMonToolBase.h

Adding @laforge ,@goetz as watchers

added DQ Egamma Reconstruction main review-pending-level-1 labels

removed review-pending-level-1 label

added review-approved label

CI Result SUCCESS (hash 4d3fe067)

	Athena
externals
cmake
make
tests

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Athena: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-EL9 2814]

merged

mentioned in commit 07c5cc40