Remove fetch-depth from _calc_docker_img (#96588)
As in current form it will only work for PRs with one commit.
Checkout full PyTorch repo (but skip submodules)
Example of failure in PR with multiple commits, see https://github.com/pytorch/pytorch/actions/runs/4389777316/jobs/7687694067#step:4:68
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96588
Approved by: https://github.com/huydhn, https://github.com/izaitsevfb, https://github.com/osalpekar
