Drop python3.8 support core and providers

[jscheffl]

As Python 3.8 is getting out-of support, this PR removes support from Airflow providers and code.

See Python release schedule: https://peps.python.org/pep-0569/

Note: As I got a head-ache thinking about how to un-bundle the removal w/o 4-5PRs this is a combination with to commits from PR #42738 and #42739 - Maybe both is needed to make CI in Airflow v2-10 branch happy anyway.

[potiuk]

Note: As I got a head-ache thinking about how to un-bundle the removal w/o 4-5PRs this is a combination with to commits from PR #42738 and #42739 - Maybe both is needed to make CI in Airflow v2-10 branch happy anyway.

Ah yeah. This is indeed needed to be done in a single PR

[potiuk]

Additionally ... This one should be done as a PR from apache repository - not from your fork. The reason is that "Build images" workflow uses "pull_request_target" workflow type and for that one - we need to make sure all the build scripts are taken from "target" branch (i.e. "main" branch in this case) - because otherwise anyone who modifies the build scripts in the PR will be able to run their code in "pull_request_target" workflow - with access to our secrets and write permissions.

So you will need to close that PR and re-open it by pushing your branch to the "apache" repository and open PR from there. When you will do it, the "pull_request_target" workflow will not be used at all - instead images will be built in the "Tests" workflow - and pushed to registry. This is because only PRS from the "main" repository can have write permissions (in this case "packages:write"). By default "pull_request" workflows have no "write" permissions and they would not be able to push the images to our registry - that's why for the "Fork" pull requests we need to build and push images in "pull_request_target" workflow - because it can have write permissions - but we have to make sure that this workflow uses only "approved" workflows and scripts from the "main" branch - rather than those that the PR is modifying.

What happens in "pull_request_target" is that we check-out the PR from the fork, and before we run any scripts in our workflows, we override workflows, actions and scripts/ci folder with the version from main - this way the "PR modified" code cannot modify workflows and scripts used during the "pull_request_target".

[jscheffl]

So you will need to close that PR and re-open it by pushing your branch to the "apache" repository

Oh, wow. New learning. Did not know that with my committer power I actually could do...

Continued in #42766