handle error: storage belongs to different cluster

Author: BalabaDmitri

tests/integration/ha_tests/test_self_healing.py

@@ -80,7 +80,7 @@ async def test_build_and_deploy(ops_test: OpsTest) -> None:
         async with ops_test.fast_forward():
             await ops_test.model.deploy(
                 charm,
-                num_units=1,
+                num_units=3,
                 series=CHARM_SERIES,
                 storage={"pgdata": {"pool": "lxd-btrfs", "size": 2048}},
                 config={"profile": "testing"},