tests: fixed waiting for new controller to be elected

We need to wait for the new controller to be elected if the stopped node
was the one before. Retry policy in admin client would fail as all the
requested nodes would redirect request to old controller which is
unavailable.

Fixes: redpanda-data#5695

Signed-off-by: Michal Maslanka <michal@redpanda.com>

tests/rptest/tests/partition_movement_test.py

@@ -743,7 +743,16 @@ def test_availability_when_one_node_down(self):
         self.logger.info(f"stopping node: {to_stop}")
         self.redpanda.stop_node(self.redpanda.get_node(to_stop))
 
-        wait_until(lambda: self.redpanda.controller() != to_stop, 30, 1)
+        def new_controller_available():
+            controller_id = admin.get_partition_leader(namespace="redpanda",
+                                                       topic="controller",
+                                                       partition=0)
+            self.logger.debug(
+                f"current controller: {controller_id}, stopped node: {to_stop}"
+            )
+            return controller_id != -1 and controller_id != to_stop
+
+        wait_until(new_controller_available, 30, 1)
         # ask partition to move
         admin.set_partition_replicas(self.topic, partition_id, assignments)