Run libtorch trunk build on linux.4xlarge (#88683)
Add optional `runner` input to `_linux-build.yml`
Move `libtorch-linux-bionic-cuda11_6-py3_7-gcc7-build` to `linux.4xlarge` as it occasionally OOMS on 2xlarge one
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88683
Approved by: https://github.com/atalman, https://github.com/weiwangmeta
