Add serverless FTR tests to staging quality gate

[pheyos]

Summary

This PR adds the serverless FTR tests that we already have in the QA quality gate to the staging quality gate.

Details

We intentionally decided run the same set of FTR tests again in staging for starters. We're accepting the over-testing here until we have enough confidence and experience with our serverless product stability to decide which set of tests to run in which environment.

This PR also explicitly sets the EC_ENV and EC_REGION environment variables for QA and Staging. It worked fine for QA env so far without setting the environment variable because it fell back on the QAF default values. Setting these values explicitly, makes it more robust.

[pheyos]

@elasticmachine merge upstream

[pheyos]

@elasticmachine merge upstream

[pheyos]

@elasticmachine merge upstream

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 6a68f2f

Failed CI Steps

• FTR Configs #56

Test Failures

• [job] [logs] FTR Configs #56 / serverless common UI Index Management Index Templates "before all" hook for "renders the index templates tab"

Metrics [docs]

✅ unchanged

History

• 💔 Build #163286 failed 0091740
• 💔 Build #162996 failed c233c1d
• 💛 Build #162605 was flaky 97d95bd
• 💔 Build #162402 failed de17f67

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @pheyos