Add Merge Train support to AutoDevOps
Problem to solve
Merge trains doesn't currently support Auto DevOps and it is causing a lot of confusion for our users.
Intended users
Further details
We are planning to inform users when their .gitlab-ci.yml file is not configured to use merge trains, when the setting for merge trains is enabled.
For autoDevOps we should add the missing configuration for them.
Proposal
Following https://docs.gitlab.com/ee/ci/merge_request_pipelines/#configuring-pipelines-for-merge-requests
add only: [merge_requests] to the auto DevOps .gitlab-ci.yml file
the 1. Pipelines for merged results needs to be enabled in the settings