Remove armv7s build from iOS (#26222)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26222
### Summary
The last generation of armv7s device is Phone 5C. As discussed with David offline, we decided not to support iOS armv7s devices.
### Test plan
- CI finishes successfully
- Builds can be run only on X86_64 and arm64 devices
Test Plan: Imported from OSS
Differential Revision: D17385308
Pulled By: xta0
fbshipit-source-id: f883999aed18224ea3386b1f016964a33270fa34
