Replace `pipeline.yaml_errors` with `ci_pipeline_messages` in app/assets/javascripts/ci/merge_requests/utils.js

ci_pipeline_messages was created to replace yaml_errors in the long-term. As part of this effort we must replace instances of yaml_errors with ci_pipeline_messages so we can drop the yaml_errors column.

Proposal

Replace pipeline.yaml_errors with ci_pipeline_messages in app/assets/javascripts/ci/merge_requests/utils.js