Remove horrible old repository edit controller

Summary:
Ref T2231. I didn't port these options over, so they're still supported but have no edit UI:

• Pull Frequency (confusing/not useful, I think?)
• Default Owners Path (probably used only by Facebook and only in the E repository)
• Show user in public repository URL (probably mostly obsolete with hosting?)

We can add those back if users notice, but they seem like the three least useful options so I'm going to see if we can get away with removing them.

Test Plan: Clicked "Edit" from Repositories, got kicked into the nice new Diffusion edit UI instead of the old one.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2231

Differential Revision: https://secure.phabricator.com/D7410