Pipeline Graph Structural Update: Cleanup CSS and Accessors

What does this MR do?

This MR removes CSS glasses that have been added to Gitlab UI () and replaces a call to the accessors object with the accessValue function to keep things consistent (see: #288849 (closed)).

It should have no affect on the live graph.

Screenshots (strongly suggested)

flag on	flag off (live)

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.

Related to #276949 (closed)