Regular Merge button shows up when merge trains is enabled and pipeline for MR is waiting on a manual action

🧩 Problem

When pipeline for merged result + merged train is enabled, and the pipeline for merge request is waiting on a manual action, the MR widget shows a regular merge button instead of a Start/Add to merge train.

Conditions: Pipeline for merged results: Enabled Merge trains: Enabled MR pipeline waiting on manual action

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However, when pipeline must succeed is enabled, the behaviour is as expected

Conditions: Pipeline for merged results: Enabled Merge trains: Enabled Pipeline must succeed: Enabled

⚡️ Proposal

• Replace the regular merge button with Start/Add to merge train button.
• Review Merge train possible despite blocked merge (#383137 - closed) after fix to see if it resolves that as well.