rabbit_deprecated_features: No need to check for HA polices if Khepri is enabled

[Why]
Khepri depends on the fact that classic queue mirroring is turned off
(i.e. the `classic_queue_mirroring` deprecated feature is denied or
removed).

Therefore, there is no need to query the database for something that
won't be there anyway.

[How]
We simply return `false` if Khepri is enabled.

Author: dumbbell

deps/rabbit/src/rabbit_mirror_queue_misc.erl

@@ -951,7 +951,7 @@ are_cmqs_permitted() ->
 are_cmqs_used(_) ->
     case rabbit_khepri:get_feature_state() of
         enabled ->
-            are_cmqs_used1();
+            false;
         _ ->
             %% If we are using Mnesia, we want to check manually if the table
             %% exists first. Otherwise it can conflict with the way