EventServiceMP: prevent too many MetaDataStop incidents

Avoid invoking MetaDataStop incident in EventServiceMP NextRange which made no sense there and was also causing a deadlock.

Also prevent MetaDataStop incident at finalize if OutputSequencer is in use, because OutputSequencer calls MetaDataStop itself at the end of each event sequence.
Calling it again at job finalize (from MetaDataSvc::stop()) would replace the last sequence output file with a new empty file containing only metadata.

The fix should not affect normal workflows.