Resolve "Unable to expand multiple downstream pipelines." bug

What does this MR do?

• The first is that we no longer reset the downstream or upstream pipelines when you expand a new one which prevents the graph from collapsing. This also involved removing an unused argument from a couple of function
• The second is that when you would expand an upstream pipeline, it would open all of them at once, which I fixed in app/assets/javascripts/pipelines/stores/pipeline_store.js by only opening one.
• We used to reset the pipeline store every time we clicked on a downstream, which is why you couldn't expand the downstream of a downstream (the store was empty, so we couldn't build the graph). However, I had initially completely removed it BUT we need it so that when you are expanding a sibling of a downstream, you reset the graph, otherwise the UI tries to stack both of them on top of each other.
• You can see 2 commits in the history, the first one is the bug fix, the second take care of the sibling downstreams
• Lastly, I will make an MR in 12.10 to migrate the karma spec to jest.

Screenshots

Before

After

Videos

Before Downstream-current-UX

After Downstream-after-fix

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Relates to: #119017 (closed)