Use bare pointer in ATLASUncalibSourceLink rather than element links.

Since the sourcelinks are very frequently dereferenced this leads to a significant improvement in the track finding time.

This merge request affects 5 packages:

• Tracking/Acts/ActsDataPreparation
• Tracking/Acts/ActsEventCnv
• Tracking/Acts/ActsGeometry
• Tracking/Acts/ActsTrackReconstruction
• Tracking/Acts/ActsTruth

Affected files list will not be printed in this case

Adding @toyamaza ,@adye ,@tbold ,@pagessin ,@cvarni ,@goetz ,@jojungge as watchers

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

The resulting ATLASUncalibSourecLink cannot be persistified. But currently the persistification is disabled. This problem will be addressed in a separate MR. A draft can be found in MR !71435 (merged)

CI Result SUCCESS (hash 16f72948)

	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 9711] (remote access info)

Looks good, approving - L2

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

merged

mentioned in commit 461e52cd

I suppose this MR is related to ATLIDTRKCP-526

mentioned in merge request !71435 (merged)

mentioned in merge request !71536 (merged)

This is the result of this MR. There is indeed an improvement (~6%) on the Track Finding time