Fixes alignments and strokes in mini graph for pipeline

What does this MR do?

Fixes:

• Vertical alignment issues in Firefox and Safari
• Last child stroke before downstream was visible
• Margin between downstream and text was nonexisting

Screenshots (if relevant)

Firefox

Before	After

Safari

Before	After

Chrome

Before	After

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #2971