R1:09341be10fc4

Remove repository shortcuts

Summary:
Repositories currently have a no-UI "shortcut" feature which is only used by Facebook (and I'm not sure it's even used). As implemented, this feature is policy-oblivious and kind of nonsensical. Throw it away.

I'm open to reimplementing this, but I want to see some level of interest in it before I do. The new implementation would add shortcuts to each repository, similar to how mirrors work. My original plan was to follow this up with such an implementation (it's half…