Move the `post-test` stage closer to the `test` stage

What does this MR do?

This moves the post-test stage closer to the test stage and introduces a new post-qa stage, just after the qa stage.

1. This shouldn't block the review-prepare since the review-build-cng/schedule:review-build-cng jobs have needs: ["gitlab:assets:compile pull-cache"].
2. This should save a few minutes for the overall pipeline because the coverage job takes around 9 minutes to finish, so having it run in parallel of the review-build-cng job should reduce the pipeline duration of 9 minutes.

Does this MR meet the acceptance criteria?

Conformity

• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

Closes #37375 (closed).