Use APRDefaults to name the Event Data TTree/RNTuple
Make the AtheaPool Conversion Service use by default the prefix defined in APRDefaults as the name prefix for POOL containers. This prefix in most cases corresponds to the name of the main Event Data TTree/RNTuple.
There should be no change for the standard "CollectionTree" name in normal Athena jobs. But by configuring the Output.StorageTechnology.EventData="ROOTRNTUPLE" the main RNTuple will be now by default called "EventData" (or whatever is specified in APRDefaults).
These defaults can be still overridden in the usual way by setting the Prefix property of this service.