Jonathan Desrosiers ae13cba729 Build/Test Tools: Use the Slack notifications workflow as a reusable one.
This backports several changesets that are required to remove the reliance on the `workflow_run` event for posting Slack notifications.

The Slack notification workflow will now be called as a reusable one, which has several benefits (see [53591]).

Several other minor GitHub Actions related updates are also being backported in this commit to maintain tooling consistency across branches that still receive security updates as a courtesy when necessary.

Merges [51921], [51924], [51925], [51937], [52002], [52130], [52183], [52233], [53112], [53581], [53582], [53592] to the 5.8 branch.
See #56095.

git-svn-id: https://develop.svn.wordpress.org/branches/5.8@53597 602fd350-edb4-49c9-b593-d223f7449a82
2022-06-30 16:26:30 +00:00
..
2021-03-01 16:56:08 +00:00