Skip danger changelog checks testing

What does this MR do?

We test the changes introduced in gitlab-org/ruby/gems/gitlab-dangerfiles!135 (merged). Specifically, we want to test the following scenarios:

Scenario 1 - Revert MR + CHANGELOG.md has NOT been changed

Expected outcome:

• The changelog job should pass
• We should see a warning from danger about revert MRs (not strictly necessary, but good for awareness for the time the MR will change the changelog)

Results:

Job: https://gitlab.com/gitlab-org/gitlab/-/jobs/3514036188

Scenario 2 - Revert MR + CHANGELOG.md has been changed, but no labels have been set

Expected outcome:

• The changelog job should fail
• We should see a warning from danger about revert MRs

Results:

Job: https://gitlab.com/gitlab-org/gitlab/-/jobs/3514091807

Scenario 3 - Revert MR + CHANGELOG.md has been changed, and correct labels have been set

Expected outcome:

• The changelog job should pass
• We should NOT see a warning from danger about revert MRs

Results:

Job: https://gitlab.com/gitlab-org/gitlab/-/jobs/3514140523

Scenario 4 - NOT a revert MR + CHANGELOG.md has been changed, and correct labels have been set

The pipeline:expedite isn't allowed if we are not on a merge request, so this scenario will always result in a failed job (which is a good thing.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.