Allow non maintainers to trigger downstream pipelines on protected branch

Summary

In order to trigger downstream pipelines from another repository on a protected branch, user has to be allowed to merge on the protected branch of the triggered repo.

Steps to reproduce

• Protect a branch on repo A (eg. master) with a user X allowed to merger only.
• Trigger a pipeline from repo B on repo A with a user Y who isn't allowed to merge. It fails.
• Trigger a pipeline from repo B on repo A with user X. It succeeds.

What is the expected correct behavior?

All users, even if they are not allowed to merge, should be able to run trigger pipeline on protected branch. The only workaround is to give maintainer permissions to all developers, that is often not acceptable.

Related issue

This issue has not solved the main issue : #348465 (closed)