Pin ci machines with Vulkan setup to Ubuntu 22.04

[Wumpf]

ubuntu-latest got updated to imply Ubuntu 24. This makes our software rasterizer script fail with

ERROR: [Loader Message] Code 0 : libLLVM-15.so.1: cannot open shared object file: No such file or directory
ERROR:             libLLVM-15.so.1: cannot open shared object file: No such file or directory

when running vulkaninfo. Surely we can fix this by installing the necessary dependencies, but for now let's just pin this to the previous OS version.

[github-actions]

Web viewer built successfully. If applicable, you should also test it:

• I have tested the web viewer

Result	Commit	Link	Manifest
✅	51d5cce	https://rerun.io/viewer/pr/8721	+nightly +main

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