Add child and parent labels to pipelines (3/3)

What does this MR do?

• Adds a child label to a pipeline in the graph view if it is a child pipeline. Or adds a parent label to a pipeline if it's a parent pipeline.
• Calculates node downstream pipeline node size differently since different node sizes are introduced.

Follow up issue to remove project.id comparison and string checks: #39205 (closed)

Enable feature flag Feature.enable(:ci_parent_child_pipeline) to test locally until !21830 (merged) is merged.

Screenshots

New data response for pipelines - MR !21394 (merged)

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

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