Schema pulls should always be disabled when group 0 is used. However,
`migration_manager::disable_schema_pulls()` is never called during
a restart with `recovery_leader` set in the Raft-based recovery
procedure, which causes schema pulls to be re-enabled on all live nodes
(excluding the nodes replacing the dead nodes). Moreover, schema pulls
remain enabled on each node until the node is restarted, which could
be a very long time.
The old gossip-based recovery procedure doesn't have this problem
because we disable schema pulls after completing the upgrade-to-group0
procedure, which is a part of the old recovery procedure.
Fixes#26569
(cherry picked from commit ec3a35303d)
95d4206585