Incorrect ShapeCast2D behavior against CollisionPolygon2D with build_mode = BUILD_SEGMENTS

[Pizzaandy]

Tested versions

Reproducible in:
v4.2.1.stable.mono.official [b09f793]
v4.3.dev3.mono.official [36e943b]

System information

Godot v4.2.1.stable.mono - Windows 10.0.19045 - GLES3 (Compatibility) - NVIDIA GeForce RTX 3070 (NVIDIA; 31.0.15.4665) - AMD Ryzen 7 3700X 8-Core Processor (16 Threads)

Issue description

The ShapeCast2D node does not behave correctly against CollisionPolygon2Ds built with segments.
This bug occurs regardless of the shape used in ShapeCast2D.

This may be related to #87347, as I have also noticed test_body_motion in CharacterBody2D failing to detect collisions with corners on segments. cast_motion and test_body_motion appear to share similar logic. I will open another issue for this.

ShapeCastAgainstSegments.mp4

Steps to reproduce

1. Enable Debug -> Visible Collision Shapes
2. Run the MRP and move the mouse towards each CollisionPolygon2D
3. Observe the difference between Solids and Segments

Minimal reproduction project (MRP)

MRP_SegmentsCollisionError.zip

[Pizzaandy]

May be related to #88227