[yabanana]

What

The Linux Build job stops before compilation with guest_formatting_tests is run by ctest now; remove it from KNOWN_UNRUN. The test is registered unconditionally in core/libs/prx/libc/CMakeLists.txt, but the registration checker still exempts it on non-Windows hosts.

Remove that stale exception and the now-unused sys import. Missing registration still fails the check. Reproduced while validating #1499: failing Linux job.

Tested

• macOS on Apple Silicon, Python 3.13, CMake/Ninja: a temporary configured project with the same executable/test names fails with the upstream checker and passes with this change. Removing its CTest registration fails with this change, as expected.
• python tools/check_conventions.py --base origin/main and git diff --check: pass.
• Current fork CI: https://github.com/yabanana/AnyPS5/actions/runs/37789852570 (head 59fd2022). The real Linux test-registration gate now passes and compilation has started. Full Linux/Windows builds remain in progress. No runtime or game behavior changed or claimed.

Checklist

• Based on current main (f2f7abab); no other open PR implements this correction. fix(libSceVideoOut): propagate shutdown driver error and register flip tests #1575 changes a separate exception in the same file.
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw; silent stubs are listed in TechnicalDebt (unchanged)
• No notes, investigation .md files or images added to the repository
• New third-party code is a submodule built from source (none added)
• Generic behaviour, not specific to one title
• Depends on: none
• AI-assisted: yes

[adriadam10]

Main's linux job fails since #1435 registered guest_formatting with ctest on Linux: check_test_registration.py still listed guest_formatting_tests as not run. Removing the stale exception (and the sys import only it used) is the right fix; the test is registered on every platform (core/libs/prx/libc/CMakeLists.txt:249). Merging once CI is green.