feature flags: skip tests for recently fixed bugs

These tests fail in a mixed-version cluster with 3.13

Author: mkuratczyk

deps/rabbit/test/feature_flags_SUITE.erl

@@ -1277,6 +1277,13 @@ activating_plugin_with_new_ff_enabled(Config) ->
     ok.
 
 enable_plugin_feature_flag_after_deactivating_plugin(Config) ->
+    case rabbit_ct_broker_helpers:is_feature_flag_enabled(Config, 'rabbitmq_4.0.0') of
+        true ->
+            ok;
+        false ->
+            throw({skip, "this test triggers a bug present in 3.13"})
+    end,
+
     FFSubsysOk = is_feature_flag_subsystem_available(Config),
 
     log_feature_flags_of_all_nodes(Config),
@@ -1307,6 +1314,13 @@ enable_plugin_feature_flag_after_deactivating_plugin(Config) ->
     ok.
 
 restart_node_with_unknown_enabled_feature_flag(Config) ->
+    case rabbit_ct_broker_helpers:is_feature_flag_enabled(Config, 'rabbitmq_4.0.0') of
+        true ->
+            ok;
+        false ->
+            throw({skip, "this test triggers a bug present in 3.13"})
+    end,
+
     FFSubsysOk = is_feature_flag_subsystem_available(Config),
 
     log_feature_flags_of_all_nodes(Config),