Align the upstream and downstream pipelines vertically in the mini pipeline graph

🧩 Problem

Follow-up from !72255 (merged)

The linked pipeline isn't vertically aligned with the main pipeline in the pipeline editor and other instances of the pipeline graph. Both upstream and downstream appear a bit lower than the main pipeline.

See this thread for more context.

💡 Proposal

The main mini pipeline graph should be on the same level with the downstream and upstream, (linked pipeline component).