Replace static fixture for notes_spec

## What does this MR do?

Replace `comments.html.haml` and `issue_note.html.haml` used in `notes_spec.js` by dynamically created fixture.

## What are the relevant issue numbers?

#24753

See merge request !7683

Pipelines tabs

## What does this MR do?
Changes the URL when the builds tab is clicked making it possible to be shared.

1. Adds a standard way to handle linked tabs:
    *   This behaviour is already present in the merge requests, commit and user `show` page. 
    *    This MR introduces a reusable way to accomplish this behaviour for pages with static content.

2. Adds test:
    *   For the linked tabs reusable class
    *  For the pipelines tabs

## Why was this MR needed?
To allow having a sharable URL that represented the opened tab

![tabs](/uploads/91e663c12c6e9ac46a17aa3a9489dc72/tabs.gif)

## Does this MR meet the acceptance criteria?
- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #24814

See merge request !7709

Replace static fixture for right_sidebar_spec

## What does this MR do?

Replace `right_sidebar.html.haml` for `right_sidebar_spec.js` by already existing dynamically generated fixture.

## What are the relevant issue numbers?

#24753

See merge request !7687

Replace static fixture for shortcuts_issuable_spec

## What does this MR do?

Replace `issuable.html.haml` for `shortcuts_issuable_spec.js` by already existing dynamically generated fixture.

## What are the relevant issue numbers?

#24753

See merge request !7685

Adds tests for the Linked Tabs class

Removes event listener

Adds builds

Adds test

Adds changelog entry