[47] st/theme-node-drawing: Don't skip square top left inset shadow corners
When the inner radius of the top left corner is 0, the corresponding arc does not get drawn, resulting in a path going from the bottom left corner to the top right corner when the path is closed.
Fix this by always including a line_to from the bottom left to the top left corner.
Cherry-picked from main.
Fixes: dde13b30 ("st/theme-node-drawing: Trace the correct path for inset box shadows")
Closes: #7996 (closed)