[CI] Explicitly set number of jobs for lit on Windows (#17382)

The new Windows runner is a NUMA system with 2 CPUs, and for whatever
reason `lit` seems to only detect the non-hyperthreaded cores on one of
the CPUs, so just explicitly set it.

Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>

Author: sarnex

.github/workflows/sycl-windows-build.yml

@@ -104,6 +104,7 @@ jobs:
         echo "C:\Program Files\Git\usr\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
         echo "CCACHE_DIR=D:\github\_work\cache\${{ inputs.build_cache_suffix }}" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
         echo "CCACHE_MAXSIZE=10G" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+        echo "LIT_OPTS='-j$env:NUMBER_OF_PROCESSORS $LIT_OPTS'" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
     - name: Register cleanup after job is finished
       uses: ./devops/actions/cleanup
     - uses: ./devops/actions/cached_checkout