ci: Fix mac names, bump builds to bigger runner (#81874)
Mac names were inconsistent so I changed them to be more reflective of
what they're actually testing. As well wanted to update the builders for
the build portions to run on more powerful runners to reduce tts
Some data:
* Cuts build time by 2/3 for `arm64` cross builds:
* [Trunk](https://github.com/pytorch/pytorch/runs/7447691552?check_suite_focus=true): 1h 22min
* [This PR](https://github.com/pytorch/pytorch/runs/7449648493?check_suite_focus=true): 30 min
* Similar speed ups for `x86`:
* [Trunk](https://github.com/pytorch/pytorch/runs/7447691171?check_suite_focus=true): 1h 47min
* [This PR](https://github.com/pytorch/pytorch/runs/7449647307?check_suite_focus=true): 41min
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81874
Approved by: https://github.com/albanD, https://github.com/atalman
