Metal: Stencil buffer not working when depth buffer is disabled

[stuartcarnie]

Tested versions

• v4.4.stable.official [4c311cb]
• v4.5.dev4.official [209a446]

System information

Godot v4.5.dev4 - macOS Sequoia (15.5.0) - Multi-window, 2 monitors - Metal (Forward+) - integrated Apple M4 Max (Apple9) - Apple M4 Max (16 threads)

Issue description

Using RenderingDevice to construct a pipeline that only enables stencil support does not generate the expected output.

Steps to reproduce

Run the attached MRP.

output	expected output

Minimal reproduction project (MRP)

mrp.zip

[Calinou]

I can't reproduce this on Linux + Vulkan + NVIDIA, so this is definitely Metal-specific.