Skip cluster_minority_SUITE when RABBITMQ_METADATA_STORE is set to mnesia

This suite is only meant to run with Khepri as the metadata store.
Instead of setting this explicitly we can look at the configured
metadata store and conditionally skip the entire suite. This prevents
these tests from running twice in CI.

(cherry picked from commit ecb7575)

Author: the-mikedavis

deps/rabbit/test/cluster_minority_SUITE.erl

@@ -55,13 +55,20 @@ suite() ->
 %% Testsuite setup/teardown.
 %% -------------------------------------------------------------------
 
-init_per_suite(Config0) ->
+init_per_suite(Config) ->
     rabbit_ct_helpers:log_environment(),
-    Config = rabbit_ct_helpers:set_config(Config0, [{metadata_store, khepri}]),
-    rabbit_ct_helpers:run_setup_steps(Config,
-                                      [
-                                       fun rabbit_ct_broker_helpers:configure_dist_proxy/1
-                                      ]).
+    case rabbit_ct_broker_helpers:configured_metadata_store(Config) of
+        mnesia ->
+            %% This SUITE is meant to test how Khepri behaves in a minority,
+            %% so mnesia should be skipped.
+            {skip, "Minority testing not supported by mnesia"};
+        _ ->
+            rabbit_ct_helpers:run_setup_steps(
+              Config,
+              [
+               fun rabbit_ct_broker_helpers:configure_dist_proxy/1
+              ])
+    end.
 
 end_per_suite(Config) ->
     rabbit_ct_helpers:run_teardown_steps(Config).