Determine fate of remaining Jenkins pipelines

[cachedout]

This issue concerns the following pipelines:

https://beats-ci.elastic.co/job/e2e-tests/job/e2e-testing-mbp/
https://beats-ci.elastic.co/job/e2e-tests/job/e2e-testing-pr-mbp/

We need to come to a decision about the fate of these pipelines in light of the upcoming Jenkins deprecation. The only E2E pipeline that we make us of and plan to migrate is https://beats-ci.elastic.co/job/e2e-tests/job/e2e-testing-k8s-autodiscovery-daily-mbp/ which we are tracking here.

@jlind23 you previously mentioned that you're worried about possible dependencies between the E2E pipelines and Elastic Agent builds. What need to be done here in order to come to a decision about the future of these pipelines?

cc: @elastic/observablt-ci

[pazone]

Ideally we need to make sure that all the covered functionality in e2e-testing is already covered by the new testing framework. @roaksoax Can we schedule this?

[jlind23]

Looking at the test config here it seems like only k8s test cases are still running.
The two remaining tests are the one below which are already covered by the new E2E tests in the agent repo:

- name: "Fleet"
   tags: "fleet_mode"
   platforms: ["ubuntu_22_04_amd64"]
- name: "Upgrade Agent"
   tags: "upgrade_agent"
   platforms: ["ubuntu_22_04_amd64"]

@pazone IIRC we do use a function from the E2E-testing repo inside the agent build pipeline to pull artifacts while building, this is probably something we should move to the agent repository.

[pazone]

@jlind23 This elastic/elastic-agent#2727 replaces this function. But I don't think it's a blocker if we just want to suspend the Jenkins pipeline

[jlind23]

@pazone Then we can suspend the pipeline if you agree with my above statement.

[pazone]

@jlind23 Yes, I can suspend it

[cachedout]

I have opened #3591 to remove everything that I think we want to remove.