tests/maintenance_test: increase _has_leadership_role timeout

Previously we waited for 50 seconds in total to ensure that the node has
some leaders. If it hadn't acquired any leaders "naturally", this was
not enough because the leadership balancer needs at least 1 minute to
unmute just restarted nodes and perform another tick.

(cherry picked from commit 2c6aaf7)

tests/rptest/tests/maintenance_test.py

@@ -131,8 +131,12 @@ def _enable_maintenance(self, node):
         """
         self.logger.debug(
             f"Checking that node {node.name} has a leadership role")
+        # In case the node is unlucky and doesn't get any leaders "naturally",
+        # we have to wait for the leadership balancer to do its job. We have to wait
+        # at least 1 minute for it to unmute just restarted nodes and perform another
+        # tick. Wait more than leader_balancer_idle_timeout (2 minutes) just to be sure.
         wait_until(lambda: self._has_leadership_role(node),
-                   timeout_sec=60,
+                   timeout_sec=150,
                    backoff_sec=10)
 
         self.logger.debug(