Make pipeline graph nodes bigger and responsive

Description

The Pipelines Graph truncates a lot of text when the job names are large, even if there's plenty of whitespace available. We should make the nodes larger, if there's room, up to a point. Obviously we don't want ovals that take up half the page, but we have room to make them a bit bigger without making them ugly.

Proposal

The current nodes seem to be 150px. Here's an example with 190px that still looks fine. We probably don't want to go much farther than 220px. And it sure would be awesome if it were responsive so on smaller windows we shrink it down to 150px as needed.

Links / references

/cc @annabeldunstone @lukebabb @dimitrieh