Summary:
All buck targets that points to caffe2/tools folder are now moved to tools/BUCK.
This also eliminates all python library/binary import in pt_defs.bzl, which caused T124308913.

Test Plan: CI

Differential Revision: D37468313

Pull Request resolved: https://github.com/pytorch/pytorch/pull/80408
Approved by: https://github.com/seemethere, https://github.com/malfet