[SYCL][CI] Fix ABI-compatibility testing in pre-commit

[kswiecicki]

Added UR_FORCE_FETCH_LEVEL_ZERO and corresponding
SYCL_UR_FORCE_FETCH_LEVEL_ZERO CMake options that force Level Zero
loader fetching even if a preinstalled one is found on the platform.
This fixes undefined reference errors in the ABI-compatibility testing
jobs.

[kswiecicki]

This is a fix for: #20537 (comment).
I've temporarily enabled the ABI testing jobs to see if the solution works: https://github.com/intel/llvm/actions/runs/19363228088/job/55401127202.
When it's time to enable those jobs again, removing skip_run: true should be enough.

[kswiecicki]

The question is whether we would like to fetch L0 loader on all jobs running sycl-linux-build.yml‎ or should I specialize it for the just the ABI testing jobs?

[aelovikov-intel]

@kswiecicki , is CI failure expected? If yes, then we can merge this, Nick's approval is enough for SYCL RT/CI/CMake.

[kswiecicki]

@kswiecicki , is CI failure expected? If yes, then we can merge this, Nick's approval is enough for SYCL RT/CI/CMake.

Yeah, currently L0v2 conformance tests are timing out on every UR pre-commit job (I've created an issue - #20683).