Re-enable ios-12-5 builds (#77611)
In essence, this is a revert of https://github.com/pytorch/pytorch/pull/77162
Test plan: https://github.com/pytorch/pytorch/runs/6461856319?check_suite_focus=true
Fixes #77163
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77611
Approved by: https://github.com/janeyx99
