Add help link for MRs that need a successful pipeline
As part of the epic to improve the MR widget text (https://gitlab.com/groups/gitlab-org/-/epics/6436) I've come to this message, which I need help from a ~frontend engineer to improve:
- Text: `A CI/CD pipeline must run and be successful before merge.`
- Link: https://docs.gitlab.com/ee/user/project/merge_requests/merge_when_pipeline_succeeds.html#only-allow-merge-requests-to-be-merged-if-the-pipeline-succeeds
@pedroms has suggested instead:
- Text: `Merge blocked: pipeline must succeed. [Configure CI/CD pipelines] to run a pipeline.`
- Link: https://gitlab.com/help/ci/quick_start/index.html
### Amy's research
I grepped for part of the string (`grep -rl "pipeline must run and be successful" . | grep -v "locale/"
| grep -v "tmp/"`) and got these results:
```
./app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js
./coverage-frontend/lcov-report/app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js.html
./coverage-frontend/lcov-report/ee/app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js.html
./ee/app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js
./doc/ci/troubleshooting.md
```
When I looked at the first file, I saw this string was being set as a constant: `PIPELINE_MUST_SUCCEED_CONFLICT_TEXT`. That approach made me ask "is it being used elsewhere?" This grep (`grep -rl PIPELINE_MUST_SUCCEED_CONFLICT_TEXT . | grep -v "locale/"`) turned up an extra test to modify:
```
./app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js
./coverage-frontend/lcov-report/app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js.html
./coverage-frontend/lcov-report/ee/app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js.html
./ee/app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js
./ee/spec/frontend/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js
```
But where was the link coming from? I searched for part of the string of the link, and turned up `app/views/projects/merge_requests/_widget.html.haml` with a big pile of links. The part we care about is line 14, `window.gl.mrWidgetData.pipeline_must_succeed_docs_path`.
### Amy's concern
Pedro's suggested revision would require changes to these files:
1. `./app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js`
1. `./ee/app/assets/javascripts/vue_merge_request_widget/mixins/ready_to_merge.js`
1. `./ee/spec/frontend/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js`
1. `app/views/projects/merge_requests/_widget.html.haml`
1. `./doc/ci/troubleshooting.md`
Given how the links are handled separately in `_widget.html.haml`, is it even possible to do the string with the link in the middle, as Pedro suggested? I suspect not. However, I'd really appreciate having help from a FE to figure out what I can and can't do with this string.
cc @andr3
issue