Some integrations (Snyk, Atlantis) creates extra pipeline

Why are we doing this work

Synk integration creates extra pipeline that becomes the latest pipeline.

If this merge request is set to auto merge, then the extra pipeline will trigger the auto merge and this might lead to unexpected result.

Problems:

• Snyk sends no ref to commit status API, therefore, it won't match the merge request pipeline, see thread at #13134 (comment 1607909509)
• If Synk manages to send the correct merge request ref to commit status API, there might be a race condition to create the merge request pipeline between the push event and commit status API, need to confirm.

Relevant links

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

Verification steps