Archive this repository and remove the elastic-agent-shipper binary from the release process

[cmacknz]

If the prototype of the shipper as a Filebeat implementation succeeds in elastic/beats#35135, then we will archive this repository and remove the elastic-agent-shipper binary from the elastic agent build and release process.

• Remove Jenkinsfile as this is not used anymore elastic-agent-shipper-client#30 Disable or delete all Jenkins jobs for the shipper: https://fleet-ci.elastic.co/job/elastic-agent-shipper-mbp/
• Remove the shipper from the Elastic stack release process
• Delete the shipper DRA bucket currently used in the stack release process
• https://github.com/elastic/infra/pull/39636 Remove the shipper from the elastic agent build process: https://github.com/elastic/elastic-agent/blob/7506b3d89477c8643845c632b3820a9b55ca0e27/magefile.go#L780

[cmacknz]

The release engineering team has removed the shipper binary from the DRA and release process for 8.10. We still need to remove our own CI pipelines and remove it from our internal release automation.

[jlind23]

Closing this as done as everything was cleaned up