RoiWriter+EndOfEventROIConfirmerAlg: construct handle from key

Frank Winklmeierrequested to merge
fwinkl/athena:trig_context1 into 24.0

Use (and re-use) HandleKeys for the construction of Read/WriteHandles. This allows us to pass the EventContext and should also be slightly faster than the internal key creation when constructing a handle from a plain string.

cc @tamartin

Edited by Frank Winklmeier

Merge request reports