Prevent QA check on stable branches

What does this MR do and why?

Danger checks include a QA check to verify if a QA selector was modified, and in that case, encourage the execution of the package-and-test pipeline. Stable branches automatically trigger the package-and-test pipeline to guarantee the changes are compliant from the Quality side.

Because of the above, this commit removes the QA check from stable branches, aiming to keep the Danger checks as concise as possible.

Related to gitlab-com/gl-infra/delivery#2839 (closed)

Screenshots or screen recordings

Before (!112863 (comment 1290617677))	After (tested on !113283 (closed))

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.