refactor(emqx_resource): move unused macro to test

apps/emqx_resource/include/emqx_resource.hrl

@@ -43,4 +43,3 @@
 -type after_query_fun() :: {fun((...) -> ok), Args :: [term()]}.
 
 -define(TEST_ID_PREFIX, "_test_:").
--define(DEFAULT_RESOURCE_GROUP, <<"default">>).

apps/emqx_resource/test/emqx_resource_SUITE.erl

@@ -24,6 +24,7 @@
 
 -define(TEST_RESOURCE, emqx_test_resource).
 -define(ID, <<"id">>).
+-define(DEFAULT_RESOURCE_GROUP, <<"default">>).
 
 all() ->
     emqx_common_test_helpers:all(?MODULE).