fix(router_helper): Reduce log verbosity of expected events

apps/emqx/src/emqx_router_helper.erl

@@ -144,7 +144,7 @@ handle_info({mnesia_table_event, {delete, {?ROUTING_NODE, _Node}, _}}, State) ->
     %% ignore
     {noreply, State};
 handle_info({mnesia_table_event, Event}, State) ->
-    ?SLOG(error, #{msg => "unexpected_mnesia_table_event", event => Event}),
+    ?SLOG(debug, #{msg => "unexpected_mnesia_table_event", event => Event}),
     {noreply, State};
 handle_info({nodedown, Node}, State = #{nodes := Nodes}) ->
     global:trans(