Cherry-picks multiple fixes on Danger stable checks

What does this MR do and why?

Cherry-picks multiple fixes on Danger stable checks:

• Skip danger check on documentation MRs (!112751 - merged)
• Remove pick into x.y message from Danger (!112740 - merged)
• Split QA into a dedicated section (!112742 - merged)
• Introduce a stable branch MR template (!112736 - merged)
• Highlight package-and-qa Danger message (!112855 - merged)
• Fail danger if package-and-test pipeline is can... (!113272 - merged)
• Skip package-and-test message on trivial MRs (!113431 - merged)
• Prevent QA check on stable branches (!113281 - merged)

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

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