CI: Remove CircleCI in favor of GHA ARM builds

[mroeschke]

After #60722, our unit test and wheel builds work successfully on GHA ARM runners. Additionally, now we're successfully uploading nightly ARM wheels to https://anaconda.org/scientific-python-nightly-wheels/pandas/files. Therefore, we can remove CircleCI from our CI

[WillAyd]

Looks good - we should target 2.3 right?

[jorisvandenbossche]

We first have to backport #60722 (or the wheel part of it) then, if we want to backport this as well (and we probably should yes)

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 2.3.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 f3045db91dbb89306c15b1673987cc70912a76b5

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #60761: CI: Remove CircleCI in favor of GHA ARM builds'

4. Push to a named branch:

git push YOURFORK 2.3.x:auto-backport-of-pr-60761-on-2.3.x

5. Create a PR against branch 2.3.x, I would have named this PR:

"Backport PR #60761 on branch 2.3.x (CI: Remove CircleCI in favor of GHA ARM builds)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[jorisvandenbossche]

Manual backport -> #60790

[jorisvandenbossche]

@mroeschke I also removed the circleci webhook in the settings then