R1:b8b700c179db

Remove "repository.create" Conduit API method

Summary:
Ref T10748. This has had many problems for a long time, can't create hosted repositories, can't create cluster repositories, etc. It is obsoleted by `diffusion.repository.edit`. Remove it.

(Right now `diffusion.repository.edit` isn't a strict replacement, but it will be as soon as the URI stuff cuts over.)

Test Plan: Grepped for `repository.create`.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10748

Differential Revision: https://secure.