Drop the proxying to git-http-backend via the apache configuration file
Now that pagure has the capabilities to proxy to git-http-backend
itself for both pull and push, we need to not let apache to this
before pagure gets a chance to.
Otherwise, pull will work, while push will not since the authorization
is performed by pagure itself.
Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>