Most likely 817fdad uncovered the fact that our choice of
primary replica was resonating with tablet allocation and we were ending up
picking the same replica as primary within a scope instead of rotating
primaryship among all replicas in the scope.
This created situations where for instance, restoring into a 9 nodes cluster
with primary_replica_only=true would put all data into 3 nodes, leaving
the other 6 unused. The balancing of the dataset was performed by the
subsequent repair step.
split from bhalevy/load-balance-primary-replica
Fixes#27281
Signed-off-by: Robert Bindar <robert.bindar@scylladb.com>