TrigT1CaloCalibConditions: fix compilation with gcc13

Frank Winklmeierrequested to merge
fwinkl/athena:trig_gcc13_1 into 23.0

Fix compilation with gcc13/C++20 ("arithmetic on a pointer to an incomplete type") by moving clear and destructor out-of-line.

Relates to ATLINFR-4959.

Edited by Frank Winklmeier

Merge request reports