jenkins: remove references to the Jenkins pipelines and old packaging

[v1v]

Proposed commit message

Remove the Jenkinsfile.yml files that are not used anymore
Remove the .ci/scripts that are not used anymore
Remove the old fashion make packaging goals when they were not using the DRA but the Unified Release process

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

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[vigneshshanmugam]

HB changes LGTM

[rowlandgeoff]

Victor, thanks very much for doing this cleanup. LGTM since I don't see any more active references to those scripts: https://github.com/search?q=repo%3Aelastic%2Fbeats+%22.ci%2Fscripts%22&type=code

But I'll leave our team's sign-off to @alexsapran since he mentioned in Slack he's taking a careful look.