Only use TRT_Phase in monitoring if it is available.
requested to merge goetz/athena:ATLASRECTS-6886_master_fix_unable_to_find_TRT_Phase_proxy into master
- introduce flag to toggle TRT_Phase computation or availability.
- disbale usage of TRT_Phase in TRTMonitoringRun3ESD_Alg if the TRT_Phase is not available.
- Remove unused read handle
Closes ATLASRECTS-6886