This migrates from reusable workflows to composite GHA actions. This has the following advantages:
1) We can split them into smaller, easier to reason about chunks
2) We can reuse them more freely between each other and workflows
3) They don't complicate the job names
4) In theory they'll be easier to test in isolation. While composite actions can't be unit-tested, we can easily break them up into nodejs or docker actions that can be.
As a proof of concept, some of our non-Bazel tests are migrated to GHA as well (CMake + Composer)
Closes#11718
This deletes our old branches of internal Abseil code in favor of their newly open-sourced library. Notably, this removes the ability to turn CHECK crashes into exceptions.
PiperOrigin-RevId: 504460562
Mike Kruskal