Tech debt: Use vue.js Pipelines table in commit and merge request view

At the moment we render the pipelines table in two different ways:

• In the Pipelines index, we use Vue.js and an API
• In the Commit view, under the "Pipelines" tab, we use Haml
• In the Merge Request view, under the "Pipelines" tab, we use Haml

This causes us some problems, since everytime we found a problem in one, we need to fix it twice in two different ways. The same goes for improvements.

At the moment we already have different ways of:

Making sure when the dropdown is clicked to close we do not make a new request - #26601 (closed)

• In Haml views it uses the dropdown event: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8545/diffs#61664206a6c8261bfdbed147f15a84ef87b76819_36_33
• In Vue.js view it uses HTML attributes to verify when the dropdown has been clicked - https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/assets/javascripts/vue_pipelines_index/stage.js.es6#L30

Guarantee dropdown stays opened for UX: https://gitlab.com/gitlab-org/gitlab-ce/issues/24166

• In Haml views it is not yet implemented
• In Vue.js view it's already merged: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8651

New issues:

• #27048 (closed) - see this comments: https://gitlab.com/gitlab-org/gitlab-ce/issues/27048#note_21937001 https://gitlab.com/gitlab-org/gitlab-ce/issues/27048#note_21938719

In order to do this, we need API for:

• commit/id/pipelines
• merge_requests/id/pipelines

@fatihacet @ayufan @grzesiek @jschatz1 @markpundsack We should schedule this soon than later, the longer we keep two ways of doing this the more it will hurt to merge them 🙊