[llvm] Increase git fetch depth (PR #70946)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 approved this pull request.

LGTM with one comment.

This is a fairly bandaid fix. The `changed-files` action takes an incredible amount of time to pull commits. Still haven't gotten to the bottom of that, my current fix is to just move it to before the checkout to force it to grab the info from the API. While testing the code formatting action, I've also seen quite a few cases where a fetch-depth of 2000 still won't be good enough to find the merge base. That case is uncommon though.

I have a proper fix in https://github.com/llvm/llvm-project/pull/69766, but of course it broke fetching anything as soon as I pushed it, so it's been reverted for now. Still working on debugging it/reading up on what could be going wrong.

Landing this in the meantime sounds good to me though.

https://github.com/llvm/llvm-project/pull/70946