tests: use 3 AZs in test_storage_controller_node_deletion

test_runner/regress/test_storage_controller.py

@@ -2394,6 +2394,7 @@ def test_storage_controller_node_deletion(
     Test that deleting a node works & properly reschedules everything that was on the node.
     """
     neon_env_builder.num_pageservers = 3
+    neon_env_builder.num_azs = 3
     env = neon_env_builder.init_configs()
     env.start()
 
@@ -2407,6 +2408,9 @@ def test_storage_controller_node_deletion(
             tid, placement_policy='{"Attached":1}', shard_count=shard_count_per_tenant
         )
 
+    # Sanity check: initial creations should not leave the system in an unstable scheduling state
+    assert env.storage_controller.reconcile_all() == 0
+
     victim = env.pageservers[-1]
 
     # The procedure a human would follow is: