Revert fault tolerance check to only check availability (#1514)

* Revert fault tolerance check to only check availability

controllers/bounce_processes.go

@@ -255,9 +255,13 @@ func getAddressesForUpgrade(logger logr.Logger, r *FoundationDBClusterReconciler
 		return nil, &requeue{curError: err}
 	}
 
-	if !internal.HasDesiredFaultToleranceFromStatus(logger, databaseStatus, cluster) {
-		r.Recorder.Event(cluster, corev1.EventTypeNormal, "UpgradeRequeued", "Database is unavailable or doesn't have expected fault tolerance")
-		return nil, &requeue{message: "Deferring upgrade until database is available or expected fault tolerance is met"}
+	// We don't want to check for fault tolerance here to make sure the operator is able to restart processes if some
+	// processes where restarted before the operator issued the cluster wide restart. For version incompatible upgrades
+	// that would mean that the processes restarted earlier are not part of the cluster anymore leading to a fault tolerance
+	// drop.
+	if !databaseStatus.Client.DatabaseStatus.Available {
+		r.Recorder.Event(cluster, corev1.EventTypeNormal, "UpgradeRequeued", "Database is unavailable")
+		return nil, &requeue{message: "Deferring upgrade until database is available"}
 	}
 
 	notReadyProcesses := make([]string, 0)