Sphinx runs on ubuntu 24.04 arm (#12530)

* Speed up our Sphinx GitHub Action with ARM

# `runs-on: ubuntu-24.04-arm`
https://docs.github.com/en/actions/using-github-hosted-runners/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources

* updating DIRECTORY.md

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Co-authored-by: cclauss <cclauss@users.noreply.github.com>