Allow configuring classic queue data dir in Cuttlefish config

Same as the parent commit but for classic queue data directories.

Author: the-mikedavis

deps/rabbit/priv/schema/rabbit.schema

@@ -2620,6 +2620,20 @@ end}.
     {datatype, {enum, [true, false]}}
 ]}.
 
+%% Classic queue data directory
+{mapping, "classic_queue.data_dir", "rabbit.classic_queue_data_dir", [
+  {datatype, string}
+]}.
+
+{translation, "rabbit.classic_queue_data_dir",
+    fun(Conf) ->
+        case cuttlefish:conf_get("classic_queue.data_dir", Conf, undefined) of
+            undefined -> cuttlefish:unset();
+            Val       -> Val
+        end
+    end
+}.
+
 %%
 %% Backing queue version
 %%

deps/rabbit/src/rabbit_vhost.erl

@@ -679,8 +679,13 @@ msg_store_dir_wildcard() ->
     rabbit_data_coercion:to_list(filename:join([msg_store_dir_base(), "*"])).
 
 msg_store_dir_base() ->
-    Dir = rabbit:data_dir(),
-    filename:join([Dir, "msg_stores", "vhosts"]).
+    case application:get_env(rabbit, classic_queue_data_dir) of
+        {ok, Dir} ->
+            Dir;
+        undefined ->
+            Dir = rabbit:data_dir(),
+            filename:join([Dir, "msg_stores", "vhosts"])
+    end.
 
 config_file_path(VHost) ->
     VHostDir = msg_store_dir_path(VHost),

deps/rabbit/test/config_schema_SUITE_data/rabbit.snippets

@@ -1111,6 +1111,16 @@ credential_validator.regexp = ^abc\\d+",
    [],
    []},
 
+  %%
+  %% Classic queue data dir
+  %%
+  {classic_queue_data_dir,
+   "classic_queue.data_dir = /data/rabbitmq/classic",
+   [{rabbit, [
+      {classic_queue_data_dir, "/data/rabbitmq/classic"}
+     ]}],
+   []},
+
   %%
   %% Quorum queue
   %%