LfsApiServlet: Restore good permission backend check for project access

The merge commit in Ide07ebca (a17d2b6) has overwritten the fix
brought by commit If14390356 (b844ed9) that was fixing the permission
backend check for the Git LFS API.

This commit restores the patch of If14390356 (b844ed9).

Change-Id: Id61ffab3bcbc8e0f2385569350d1e300ca3dd439
1 file changed