[Security Solution] Parallel serverless script adjustments

[MadameSheema]

Summary

In this PR we are introducing the following changes:

• Some renaming to align with the current serverless vocabulary
• Adding extra guards to be able to get rid of the hardcoded delay

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)

[patrykkopycinski]

🙇

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 431309a

Failed CI Steps

• Serverless Security Cypress Tests #4
• Investigations - Security Solution Cypress Tests #8

Test Failures

• [job] [logs] Investigations - Security Solution Cypress Tests #8 / Alert details expandable flyout right panel should add to new case should add to new case
• [job] [logs] Serverless Security Cypress Tests #4 / Use Value list in exception entry Should use value list in exception entry, and validate deleting value list prompt Should use value list in exception entry, and validate deleting value list prompt

Metrics [docs]

✅ unchanged

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

cc @MadameSheema