splines: bezier_clip: change to clip just inside instead of just outside the node

splines: bezier_clip: change to clip just inside instead of just outside the node

The previous changes removed *all* overlap between nodes and edges at
the expense of creating a very small gap instead. This is visually not
very pleasing. This change ensures that we get a very small minimum
overlap instead.

The test_min_edge_node_overlap_simple and
test_min_edge_node_overlap_node_shapes tests tests now succeed, so the
expectancy that they should fail is removed.

Towards https://gitlab.com/graphviz/graphviz/-/issues/372.