rabbit_db_maintenance: Use local queries with Khepri

[Why]
Ra consistent queries are currently fragile in the sense that the query
function may run on a remote node and the function reference or MFA may
not be valid on that node. See previous commit for more details.

[How]
We perform local queries in `rabbit_db_maintenance:get_consistent/1`
when Khepri is enabled. This violates what the expectation from this
API, that's why it is a temporary measure, until a proper solution is
found.

Author: dumbbell

deps/rabbit/src/rabbit_db_maintenance.erl

@@ -155,7 +155,12 @@ get_consistent_in_mnesia(Node) ->
 
 get_consistent_in_khepri(Node) ->
     Path = khepri_maintenance_path(Node),
-    case rabbit_khepri:get(Path, #{favor => consistency}) of
+    %% FIXME: Ra consistent queries are fragile in the sense that the query
+    %% function may run on a remote node and the function reference or MFA may
+    %% not be valid on that node. That's why we force a local query for now.
+    %Options = #{favor => consistent},
+    Options = #{favor => local},
+    case rabbit_khepri:get(Path, Options) of
         {ok, #node_maintenance_state{status = Status}} ->
             Status;
         _ ->

deps/rabbit/src/rabbit_maintenance.erl

@@ -9,6 +9,13 @@
 
 -include_lib("rabbit_common/include/rabbit.hrl").
 
+%% FIXME: Ra consistent queries are currently fragile in the sense that the
+%% query function may run on a remote node and the function reference or MFA
+%% may not be valid on that node. That's why consistent queries in this module
+%% are in fact local queries when Khepri is enabled.
+%%
+%% See `rabbit_db_maintenance:get_consistent_in_khepri/1'.
+
 -export([
     is_enabled/0,
     drain/0,