Flickering occlusion of Metal CustomLayer by terrain

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## Environment

- Xcode version: 16.3
- iOS version:
- Devices affected: iPhones, iPad, Macs
- Maps SDK Version: 11.11.0+ and 11.12.beta.1

## Observed behavior and steps to reproduce

Occlusion by terrain does product a flickering issue with metal custom layer with `depthCompareFunction = .less`

## Expected behavior

Terrain should occlude the metal layer like any other layer when the metal layer depth stencil descriptor is set to .less.

## Notes / preliminary analysis

We have a flickering correct/wrong display of the intersection of our Metal CustomLayer with the terrain like shown on the video below. We tried the same example with only 2 triangles forming a rectangle with the same effect. (depth map and

An interesting note maybe, as it could very well be connected to the same source problem: occlusion by near or far mountains does also flickers between correct (mountains correctly occluding the part of the track being hidden by them) and wrong (track visible in totality).

## Additional links and references

https://github.com/user-attachments/assets/353d528a-24a2-4afb-a1c3-da3a814258db

Start by reproducing the reported terrain occlusion flicker with a Metal CustomLayer using depthCompareFunction = .less on the listed Maps SDK versions, referring to the attached video. Compare the custom layer and terrain intersection, including near and far mountains; done means terrain consistently occludes the layer without alternating between correct and incorrect display.

Written by the indexing model from the issue text.