chore: drop few commented out and irrelevant pieces

apps/emqx/src/emqx_cm.erl

@@ -46,8 +46,6 @@
     set_chan_stats/2
 ]).
 
-% -export([get_chann_conn_mod/2]).
-
 -export([
     open_session/3,
     discard_session/1,

apps/emqx/test/emqx_cth_suite.erl

@@ -340,7 +340,6 @@ default_appspec(emqx_conf, SuiteOpts) ->
         node => #{
             name => node(),
             cookie => erlang:get_cookie(),
-            % FIXME
             data_dir => unicode:characters_to_binary(maps:get(work_dir, SuiteOpts, "data"))
         }
     },