test: fix failing custom endpoint test (#758)

Author: crystall-bitquill

Diff for: tests/integration/container/test_custom_endpoint.py

@@ -201,6 +201,7 @@ def test_custom_endpoint_read_write_splitting__with_custom_endpoint_changes(
         # This setting is not required for the test, but it allows us to also test re-creation of expired monitors since
         # it takes more than 30 seconds to modify the cluster endpoint (usually around 140s).
         props["custom_endpoint_idle_monitor_expiration_ms"] = 30_000
+        props["wait_for_custom_endpoint_info_timeout_ms"] = 30_000
         conn = AwsWrapperConnection.connect(target_driver_connect, **kwargs, **props)
 
         endpoint_members = self.endpoint_info["StaticMembers"]

Diff for: tests/integration/container/utils/rds_test_utility.py

@@ -163,6 +163,9 @@ def failover_cluster_and_wait_until_writer_changed(
             sleep(1)
             cluster_address = socket.gethostbyname(cluster_endpoint)
 
+        # wait until all instances except initial writer instance to be available
+        instances = [x.get_instance_id() for x in TestEnvironment.get_current().get_instances() if x.get_instance_id() != initial_writer_id]
+        self.make_sure_instances_up(instances)
         self.logger.debug("Testing.FinishedFailover", initial_writer_id, str((perf_counter_ns() - start) / 1_000_000))
 
     def failover_cluster(self, cluster_id: Optional[str] = None, target_id: Optional[str] = None) -> None: