build: relocate BUILT_ON template

rebar.config.erl

@@ -326,6 +326,7 @@ relx_overlay(ReleaseType) ->
     , {template, "data/loaded_plugins.tmpl", "data/loaded_plugins"}
     , {template, "data/loaded_modules.tmpl", "data/loaded_modules"}
     , {template, "data/emqx_vars", "releases/emqx_vars"}
+    , {template, "data/BUILT_ON", "releases/{{release_version}}/BUILT_ON"}
     , {copy, "bin/emqx", "bin/emqx"}
     , {copy, "bin/emqx_ctl", "bin/emqx_ctl"}
     , {copy, "bin/node_dump", "bin/node_dump"}
@@ -351,7 +352,6 @@ etc_overlay(ReleaseType) ->
                 [community_plugin_etc_overlays(App) || App <- relx_plugin_apps_extra()],
     [ {mkdir, "etc/"}
     , {mkdir, "etc/plugins"}
-    , {template, "{{base_dir}}/lib/emqx/etc/BUILT_ON", "releases/{{release_version}}/BUILT_ON"}
     , {copy, "{{base_dir}}/lib/emqx/etc/certs","etc/"}
     ] ++
     lists:map(