Do not sync roles for standby

Standby cluster is streaming from the master and does not require
to create or use databases of it's own. Hence, bypass the creation
of users or databases.

Though the standby cluster would work without this also, but will have
errors in logs, this is to avoid that.

pkg/cluster/sync.go

@@ -428,6 +428,10 @@ func (c *Cluster) syncSecrets() error {
 func (c *Cluster) syncRoles() (err error) {
 	c.setProcessName("syncing roles")
 
+	if c.Spec.StandbyCluster != nil {
+		c.logger.Info("no need to sync roles for standby cluster")
+		return nil
+	}
 	var (
 		dbUsers   spec.PgUserMap
 		userNames []string