fix(emqx_utils): use deep_merge in unindent

apps/emqx_utils/src/emqx_utils_maps.erl

@@ -345,7 +345,7 @@ indent(IndentKey, PickKeys, Map) ->
 
 -spec unindent(term(), map()) -> map().
 unindent(Key, Map) ->
-    maps:merge(
+    deep_merge(
         maps:remove(Key, Map),
         maps:get(Key, Map, #{})
     ).

apps/emqx_utils/test/emqx_utils_maps_tests.erl

@@ -170,5 +170,9 @@ map_indent_unindent_test_() ->
         ?_assertEqual(
             #{a => 1, b => 2},
             unindent(c, M)
+        ),
+        ?_assertEqual(
+            #{a => #{c => 3, d => 4}},
+            unindent(b, #{a => #{c => 3}, b => #{a => #{d => 4}}})
         )
     ].