Implement CI new integration test mega / validation runs

[Samyoul]

Problems:

• As a developer, I want to be able to identify programmatically when a PR has introduced or altered an integration test, so that CI can target those tests for additional work.
• As a developer, I want CI to run validation tests on any new or altered integration test I introduce to this repo, so that these test runs are ensured by the CI and do not rely on flaky developer memory. 😄
  • See the Test Policy

Dependant On

• Introduce Test Types #4935

Ref:

#4908 (comment)