Fix toggling of expand/hide pipeline graph button

## What does this MR do?

Corrects the toggling behaviour given that the pipeline graph now starts in a different state.

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

Expand/hide toggling UI is buggyyy

## Screenshots (if relevant)

![2016-10-14_18.15.41](/uploads/7cdeef02c0b8aa4266f2878866e4b633/2016-10-14_18.15.41.gif)

## Does this MR meet the acceptance criteria?

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

## What are the relevant issue numbers?


Closes #23358

See merge request !6898