Remove `req.resume` from `app.enableAuth`

Remove `req.pause` and `req.resume` from `app.enableAuth`
 - they are no longer needed, the request starts paused and there is
   no other middleware that would resume it before us.
 - when we resume the request after authentication, we force all
   other async operations (like sharedCtor) to call pause & resume too,
   otherwise data are lost