Rely on jenkinsci organization release drafter configuration

[MarkEWaite]

Rely on jenkinsci organization release drafter configuration

Release drafter v7 dropped support for _extends: .github in the configuration. It either needs to be removed or replaced with a more complete specification like:

_extends: github:jenkinsci/.github:/.github/release-drafter.yml

This pull request removes it because the "Enabling CD" instructions say:

You can delete any existing Release Drafter configuration ... as that will be subsumed by the CD workflow

Adapts to release drafter changes in pull request:

• feat: new major version release-drafter/release-drafter#1475

Follows the pattern in credentials plugin pull request:

• Deleting Release Drafter config credentials-plugin#1037

Automatic releases will fail until this is merged if the plugin is using the 1.8.2 release of reusable workflows.

Testing done

• None. Has worked well in many repositories, not expecting any issues in this repository

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes