fix(etc): remove .d suffix from dir names

rebar.config.erl

@@ -243,11 +243,11 @@ extra_overlay(edge) ->
     [].
 emqx_etc_overlay(cloud) ->
     emqx_etc_overlay_common() ++
-    [ {"etc/emqx_cloud.d/vm.args","etc/vm.args"}
+    [ {"etc/emqx_cloud/vm.args","etc/vm.args"}
     ];
 emqx_etc_overlay(edge) ->
     emqx_etc_overlay_common() ++
-    [ {"etc/emqx_edge.d/vm.args","etc/vm.args"}
+    [ {"etc/emqx_edge/vm.args","etc/vm.args"}
     ].
 
 emqx_etc_overlay_common() ->