Skip metadata_store_clustering_SUITE in mixed versions testing

Khepri is not yet compatible with mixed-version testing and this suite
only tests clustering when Khepri is the metadata store in at least some
of the nodes.

(cherry picked from commit bda1f7c)

Author: the-mikedavis

deps/rabbit/test/metadata_store_clustering_SUITE.erl

@@ -60,7 +60,14 @@ cluster_size_3_tests() ->
 
 init_per_suite(Config) ->
     rabbit_ct_helpers:log_environment(),
-    rabbit_ct_helpers:run_setup_steps(Config, []).
+    case rabbit_ct_helpers:is_mixed_versions() of
+        true ->
+            %% Khepri is not yet compatible with mixed version testing and this
+            %% suite enables Khepri.
+            {skip, "This suite does not yet support mixed version testing"};
+        false ->
+            rabbit_ct_helpers:run_setup_steps(Config, [])
+    end.
 
 end_per_suite(Config) ->
     rabbit_ct_helpers:run_teardown_steps(Config).