Moved POST /db/media/inline endpoint outside labs

refs https://github.com/TryGhost/Toolbox/issues/524

- The endpoints is for internal (non-documented) usage at the moment and is fine without the labs flag.
- This should allows us to test the inlining on production sites sooner

ghost/core/core/server/web/api/endpoints/admin/routes.js

@@ -207,7 +207,6 @@ module.exports = function apiRoutes() {
 
     router.post('/db/media/inline',
         mw.authAdminApi,
-        labs.enabledMiddleware('mediaInliner'),
         http(api.db.inlineMedia)
     );