TrkParticleCreator+TRT_DetElementsRoadTool_xk: Fix cppcheck 2.14 warnings.

Prefer returning const references to members rather than copies.

This merge request affects 2 packages:

• InnerDetector/InDetRecTools/TRT_DetElementsRoadTool_xk
• Tracking/TrkTools/TrkParticleCreator

Affected files list will not be printed in this case

Adding @sroe ,@cgrefe ,@goetz ,@calfayan ,@gavrilen as watchers

added InnerDetector Tracking main review-pending-level-1 labels

CI Result SUCCESS (hash b773c95b)

	Athena
externals
cmake
make
tests

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Athena: number of compilation errors 0, warnings 0
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Approving from L1 side (Fábio).

removed review-pending-level-1 label

added review-approved label

merged

mentioned in commit 0768a02b