Fix ogre2 heightmap test on metal (backport #1179)

[mergify]

🦟 Bug fix

Fixes #1174 and #1159

Summary

I verified locally that the ogre2 engine was able to successfully generate images on mac when running the INTEGRATION_heightmap test. The test failed because when comparing the colors between an image generated by a regular camera and the color component of the point cloud data generated by a depth camera, one particular pixel has a higher error than the current allowed tolerance. Fixed by increasing this error tol from 9 -> 10.

These are the images generated:

Regular RGB image:

Point cloud RGB data:

To run the heightmap test on mac:

GZ_ENGINE_TO_TEST=ogre2 GZ_ENGINE_BACKEND=metal ./build/gz-rendering/bin/INTEGRATION_heightmap

The error about unable to find metal_stdlib in the ogre2.log (mentioned in #1159) seems to be unrelated as I see this when launching gz sim with other worlds too, e.g. shapes.sdf. It could be a different issue.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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This is an automatic backport of pull request #1179 done by [Mergify](https://mergify.com).