Pipeline Graph: Stop calling parseData twice

What does this MR do?

In the course of developing the new pipeline graph and adding the Job dependencies view, we started calling parseData, a somewhat expensive operation, twice. This refactor fixes that, while not outsourcing the parsing to every element that uses the LinksLayer component, if they have no reason to call it earlier.

Screenshots or Screencasts (strongly suggested)

The view stays the same.

How to setup and validate locally (strongly suggested)

1. Create a .gitlab-ci.yml file that uses needs.
2. View that file.

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)