Improve the float compression logic in copyAuxStoreThinned

This one is also related to ATEAM-587. It's the first shot at optimizing the float compression logic part in copyAuxStoreThinned. It essentially tries to avoid unnecessary casting and aux testing in the tight loop.

cc: @ssnyder

Jenkins please retry a build

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This merge request affects 1 package:

• Control/AthContainers

Adding @ssnyder as watcher

added Core master review-pending-level-1 labels

CI Result SUCCESS (hash 5903d2e3)

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 7069]

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

merged

mentioned in commit cda9c047

added sweep:ignore label