Bazel: No need to specify required feature flags in $RABBITMQ_FEATURE…

…_FLAGS

[Why]
A node now copies the feature flag states of the remote node it wants to
join.

[How]
We set the $RABBITMQ_FEATURE_FLAGS variable to the empty string because
we still need to ensure new nodes don't start with feature flags that
old nodes don't know about in mixed-version testing.

rabbitmq.bzl

@@ -274,18 +274,12 @@ def rabbitmq_integration_suite(
         data = native.glob(["test/{}_data/**/*".format(name)]) + data,
         test_env = dict({
             "SKIP_MAKE_TEST_DIST": "true",
-            # The feature flags listed below are required. This means they must be enabled in mixed-version testing
-            # before even starting the cluster because newer nodes don't have the corresponding compatibility/migration code.
-            "RABBITMQ_FEATURE_FLAGS":
-            # required starting from 3.11.0 in rabbit:
-            "quorum_queue,implicit_default_bindings,virtual_host_metadata,maintenance_mode_status,user_limits," +
-            # required starting from 3.12.0 in rabbit:
-            "feature_flags_v2,stream_queue,classic_queue_type_delivery_support,classic_mirrored_queue_version," +
-            "stream_single_active_consumer,direct_exchange_routing_v2,listener_records_in_ets,tracking_records_in_ets," +
-            # required starting from 3.12.0 in rabbitmq_management_agent:
-            # empty_basic_get_metric, drop_unroutable_metric
-            # required starting from 4.0 in rabbit:
-            "message_containers,stream_update_config_command,stream_filtering,stream_sac_coordinator_unblock_group,restart_streams",
+	    # Don't enable any feature flags by default. This is useful for
+	    # mixed-version cluster testing to make sure that new nodes don't
+	    # enable feature flags that old nodes don't know about, preventing
+	    # cluster formation. Testsuits are responsible for enabling the
+	    # feature flags they rely on anyway.
+	    "RABBITMQ_FEATURE_FLAGS": "",
             "RABBITMQ_RUN": "$(location :rabbitmq-for-tests-run)",
             "RABBITMQCTL": "$TEST_SRCDIR/$TEST_WORKSPACE/{}/broker-for-tests-home/sbin/rabbitmqctl".format(package),
             "RABBITMQ_PLUGINS": "$TEST_SRCDIR/$TEST_WORKSPACE/{}/broker-for-tests-home/sbin/rabbitmq-plugins".format(package),