TrigT2CaloCommon: Fix test for handle validity.

Use isValid(), not cptr(). Otherwise, we can generate warning messages. Also fix clang warning from missing override keyword.

This merge request affects 1 package:

• Trigger/TrigAlgorithms/TrigT2CaloCommon

Adding @joheinri ,@damazio as watchers

added Trigger master review-pending-level-1 labels

CI Result SUCCESS (hash 732b2452)

	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 6062]

All look good, approving --L1

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

merged

mentioned in commit 3243452b

added sweep:ignore label