test(gcp consumer): attempt to stabilize flaky test

```
%%% emqx_bridge_kafka_impl_consumer_SUITE ==> ssl.t_start_and_consume_ok: FAILED
%%% emqx_bridge_kafka_impl_consumer_SUITE ==> {{panic,
     #{msg => "Unexpected result",
       result =>
           {run_stage_failed,error,
               {badmatch,{{1,0},timeout}},
               [{emqx_bridge_kafka_impl_consumer_SUITE,
                    '-t_start_and_consume_ok/1-fun-12-',4,
                    [{file,
                         "/emqx/apps/emqx_bridge_kafka/test/emqx_bridge_kafka_impl_consumer_SUITE.erl"},
                     {line,1184}]},
                {emqx_bridge_kafka_impl_consumer_SUITE,
                    t_start_and_consume_ok,1,
                    [{file,
                         "/emqx/apps/emqx_bridge_kafka/test/emqx_bridge_kafka_impl_consumer_SUITE.erl"},
                     {line,1171}]}]}}},
 [{emqx_bridge_kafka_impl_consumer_SUITE,t_start_and_consume_ok,1,
      [{file,
           "/emqx/apps/emqx_bridge_kafka/test/emqx_bridge_kafka_impl_consumer_SUITE.erl"},
       {line,1240}]},
```

apps/emqx_bridge_gcp_pubsub/test/emqx_bridge_gcp_pubsub_consumer_SUITE.erl

@@ -519,6 +519,7 @@ wait_acked(Opts) ->
     %% no need to check return value; we check the property in
     %% the check phase.  this is just to give it a chance to do
     %% so and avoid flakiness.  should be fast.
+    ct:pal("waiting ~b ms until acked...", [Timeout]),
     Res = snabbkaffe:block_until(
         ?match_n_events(N, #{?snk_kind := gcp_pubsub_consumer_worker_acknowledged}),
         Timeout
@@ -1265,11 +1266,12 @@ t_multiple_topic_mappings(Config) ->
 
 %% 2+ pull workers do not duplicate delivered messages
 t_multiple_pull_workers(Config) ->
-    ct:timetrap({seconds, 120}),
+    ct:timetrap({seconds, 121}),
     BridgeName = ?config(consumer_name, Config),
     TopicMapping = ?config(topic_mapping, Config),
     ResourceId = resource_id(Config),
     ?check_trace(
+        #{timetrap => 120_000},
         begin
             NConsumers = 3,
             start_and_subscribe_mqtt(Config),
@@ -1277,7 +1279,7 @@ t_multiple_pull_workers(Config) ->
                 snabbkaffe:subscribe(
                     ?match_event(#{?snk_kind := "gcp_pubsub_consumer_worker_subscription_ready"}),
                     NConsumers,
-                    40_000
+                    infinity
                 ),
             {ok, _} = create_bridge(
                 Config,
@@ -1287,6 +1289,14 @@ t_multiple_pull_workers(Config) ->
                         <<"ack_deadline">> => <<"10m">>,
                         <<"ack_retry_interval">> => <<"1s">>,
                         <<"consumer_workers_per_topic">> => NConsumers
+                    },
+                    <<"resource_opts">> => #{
+                        %% Used by worker when patching subscritpion; we increase it a bit
+                        %% here because (at least) the gcp emulator tends to time out /
+                        %% throttle (?)  workers targeting the same subscription, making
+                        %% the test flakier.
+                        <<"request_ttl">> => <<"5s">>,
+                        <<"resume_interval">> => <<"1s">>
                     }
                 }
             ),
@@ -1294,6 +1304,14 @@ t_multiple_pull_workers(Config) ->
             [#{pubsub_topic := Topic}] = TopicMapping,
             Payload = emqx_guid:to_hexstr(emqx_guid:gen()),
             Messages = [#{<<"data">> => Payload}],
+            ?retry(
+                500,
+                20,
+                ?assertMatch(
+                    {ok, connected},
+                    health_check(Config)
+                )
+            ),
             pubsub_publish(Config, Topic, Messages),
             {ok, Published} = receive_published(),
             ?assertMatch(