clean up old Jenkins resources

[jlind23]

Clean up old Jenkins resources and references as we don't use it anymore.

Closes: https://github.com/elastic/ingest-dev/issues/4033

[mergify[bot]]

This pull request does not have a backport label. If this is a bug or security fix, could you label this PR @jlind23? 🙏. For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit

[mergify[bot]]

backport-8.x has been added to help with the transition to the new branch 8.x. If you don't need it please use backport-skip label and remove the backport-8.x label.

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)