Disallowing the quorum aware failover option for the native replication mode.

Disallowing the quorum aware failover option for the native replication mode.

In native replication mode, Pgpool-II is responsible for replicating the data
on all backend nodes, and if a node becomes quarantined then Pgpool-II stops
sending the writes to that node and when that quarantined node becomes available
again there is no way to figure out which portion of data was not replicated
during the quarantine period. This is dangerous since it can cause
data inconsistency.

So as per the discussion, we reached the conclusion to disallow failover require
consensus and quorum existence with the native replication mode so that backend
node should never get into quarantine when Pgpool-II is configured in the
replication mode.