[Discussion] Remove the implicit require pipeline succeeds for auto merge

When we were porting over the auto merge from Merge When Pipeline Succeeds, to Merge When Checks Pass (MWCP), we had to bring over the implicit expectation that the pipeline must succeed before merging. When we initially did not have this implicit requirement, user's expected the MWCP to adhere to this, regardless of if the user had 'Pipeline must succeed' setting or not and raised issues about the new behaviour.

Currently to decide if when to auto merge, we have to determine if a user expects a pipeline to run for their Merge Request. This is not so easy, and there isn't a clear way to achieve this.

This issue is to create discussion (trade offs/implications) around changing this implicit expection to using the setting 'Pipeline must succeed' instead.