[Security Solution] Include only @serverlessQA Cypress tests to the 2nd quality gate

[banderror]

Summary

Fixes a bug introduced in #181371 that included all Cypress tests tagged as @serverless to the 2nd quality gate (the QA stage in the release pipeline).

Current behavior: all tests tagged as @serverless run in the 2nd quality gate as part of the Kibana Serverless release process. Many of them are not ready for this and are not supposed to run there.

Correct behavior: include only those that were explicitly tagged as @serverlessQA.

Context

Tests that run in the 2nd quality gate can be found in https://buildkite.com/elastic?filter=security%20solution

For example, in this build we have a script:

$ yarn cypress:qa:serverless --spec './cypress/e2e/detection_response/rule_management/!(prebuilt_rules)/**/*.cy.ts'
--
  | $ TZ=UTC NODE_OPTIONS=--openssl-legacy-provider node ../../plugins/security_solution/scripts/start_cypress_parallel_serverless --config-file ../../test/security_solution_cypress/cypress/cypress_ci_serverless_qa.config.ts --spec './cypress/e2e/detection_response/rule_management/!(prebuilt_rules)/**/*.cy.ts'

that runs yarn cypress:qa:serverless which in turn uses the x-pack/test/security_solution_cypress/cypress/cypress_ci_serverless_qa.config.ts config which used incorrect tags to select Cypress tests.

[elasticmachine]

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

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 7d007b9

Metrics [docs]

✅ unchanged

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

cc @banderror

[MadameSheema]

@banderror @serverless does not include all the tests in the second quality gate.

To minimize the number of Cypress configuration and scripts, inside the parallel script, we are overriding the tag configuration when the tests are triggered by the second quality gate.

I understand that the names used on buildkite when the periodic pipeline is triggered might be misleading if you are not familiar with the whole process. We'll work on that to improve it.

[banderror]

Closing due to #182600 (comment). It's not a bug and there's nothing to fix, only to improve the naming of config files, scripts, pipelines, steps, etc. Thank you @MadameSheema!