Pipeline Graph: Scroll downstream pipeline into view on load

What does this MR do?

Updates the new pipeline graph so that the child pipeline scrolls into view when loaded. Behind flag, as usual.

Screenshots (strongly suggested)

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)