Enhanced mkrep.sh handling for journalcopy/standby replicas.
Changed lbr.replication value for metadata-only replicas from
'ondemand' to 'shared'. There is no behavior change as the those
are synonyms, but 'shared' more clearly conveys the intent.
Adjusted number of pull threads to be 5 for all full replicas
(i.e. not metadata-only replicas).