tests: mitigate MaintenanceTest failures

The real fix will be to make the leader balancer aware
of maintenance mode, but the test has become much more
unstable since recent leader balancer changes to do
more movements concurrently, so its worth mitigating
that.

The workaround is to set a short mute timeout so that
muting nodes has no real effect, and a short idle timeout
so that post-maintenance leader movements happen promptly.

Related: redpanda-data#4772

tests/rptest/tests/maintenance_test.py

@@ -25,7 +25,22 @@ class MaintenanceTest(RedpandaTest):
               TopicSpec(partition_count=20, replication_factor=3))
 
     def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
+        super().__init__(
+            *args,
+            extra_rp_conf={
+                # Leader balancer configuration changes are a workaround
+                # to https://github.com/redpanda-data/redpanda/issues/4772
+
+                # Faster leader balancer iteration to get partitions moved
+                # back to nodes leaving maintenance mode promptly.
+                'leader_balancer_idle_timeout': 5000,
+
+                # Mute timeout shorter than idle timeout: effectvely disable
+                # node muting.  This enables nodes leaving maintenance mode
+                # to get leaderships moved to them promptly.
+                'leader_balancer_mute_timeout': 1000,
+            },
+            **kwargs)
         self.admin = Admin(self.redpanda)
         self.rpk = RpkTool(self.redpanda)
         self._use_rpk = True