GA Migration Precommit Python Examples ( Python Precommit Sharding)

[andoni-guzman]

This PR is part of the migration from jenkins to github actions. This PR is part of the Precommit Java Sharding

This PR contains this tests

Precommit Python Examples

1 file were added to the workflows folder of github actions

job-precommit-python-examples.yml

CI.md was modified adding the new GA workflows

Waiting for this PR before merge https://github.com/apache/beam/pull/22703

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• [ ] Choose reviewer(s) and mention them in a comment (R: @username).
• [ ] Mention the appropriate issue in your description (for example: addresses #123), if applicable. This will automatically add a link to the pull request in the issue. If you would like the issue to automatically close on merging the pull request, comment fixes #<ISSUE NUMBER> instead.
• [ ] Update CHANGES.md with noteworthy changes.
• [ ] If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI.