Create a way to run the different test suites from the e2e-testing repo

[mdelapenya]

We'd like to provide a way to run one of the tests suites in the repo from a pipeline.

Scenario: run the tests suite for Ingest Manager
Given the ingest manager pipeline in the Beats CI
When a change in the elastic-agent is detected
Then run the e2e tests for ingest-manager

Too run the tests, we should:

• Clone the e2e repository (https://github.com/elastic/e2e-testing)
• Move to the directory of the test suite, under e2e/_suites and execute godog, or
• Use the in-place script:

.ci/scripts/functional-test.sh "${GO_VERSION}" "${suite}" "${feature}" "${STACK_VERSION}" "${METRICBEAT_VERSION}"

Thinking out loud, this script makes me think that we do not need many of the variables for different test executions: i.e. the METRICBEAT_VERSION is not needed for ingest-manager, the KIND_VERSION is needed by Helm, only. So maybe we should create a different pipeline for each test suite, with proper variables each, although this adds the downstream issue we have been discussing in the past. Or we could create a script for running each test suite, which sets properly the environment for the specific suite.

@elastic/observablt-robots thoughts?

[mdelapenya]

We agreed to:

1. enable the ability of running just one test suite (i.e. integrations, helm...) from the existing Jenkins pipeline. This applies to the e2e repo. Execute tests suites based on the modified files e2e-testing#130
2. evaluate how to run this filtered pipeline from Beats whenever a merge to master occurs.
3. once the merges to master run the e2e test suite, add the ability to add a comment on PRs to run the e2e tests.

[mdelapenya]

This has been accomplished in elastic/beats#21100