Only process restore request in the current alpha if it's the leader. (…

…#5657)

Requests for other groups are being sent to the leader but the request
for the group the received the request might not be sent to the leader.
Fix that by first checking if the alpha is the leader. If not, the
request is sent to the leader.

worker/online_restore_ee.go

@@ -83,7 +83,7 @@ func ProcessRestoreRequest(ctx context.Context, req *pb.RestoreRequest) error {
 }
 
 func proposeRestoreOrSend(ctx context.Context, req *pb.RestoreRequest) error {
-	if groups().ServesGroup(req.GetGroupId()) {
+	if groups().ServesGroup(req.GetGroupId()) && groups().Node.AmLeader() {
 		_, err := (&grpcWorker{}).Restore(ctx, req)
 		return err
 	}