[CI] Update sycl-windows-run-tests.yml (#16621)

Added merge_ref to inputs. Use ref instead of undeclared build_ref.

.github/workflows/sycl-rel-nightly.yml

@@ -119,8 +119,8 @@ jobs:
     if: ${{ github.repository == 'intel/llvm' && needs.check_for_new_commits.outputs.is_new_commit != 'false' }}
     uses: ./.github/workflows/sycl-windows-build.yml
     with:
+      ref: sycl-rel-6_0_0
       merge_ref: ''
-      build_ref: sycl-rel-6_0_0
 
       # We upload both Linux/Windows build via Github's "Releases"
       # functionality, make sure Linux/Windows names follow the same pattern.
@@ -140,6 +140,7 @@ jobs:
       sycl_toolchain_archive: ${{ needs.build-win.outputs.artifact_archive_name }}
       extra_lit_opts: --param gpu-intel-gen12=True
       ref: sycl-rel-6_0_0
+      merge_ref: ''
 
   cuda-aws-start:
     needs: [ubuntu2204_build]

.github/workflows/sycl-windows-run-tests.yml

@@ -18,6 +18,13 @@ on:
       ref:
         type: string
         required: False
+      merge_ref:
+        description: |
+          Commit-ish to merge post-checkout if non-empty. Must be reachable from
+          the default_branch input paramter.
+        type: string
+        default: 'FETCH_HEAD'
+        required: False
 
       sycl_toolchain_artifact:
         type: string
@@ -68,7 +75,8 @@ jobs:
     - uses: ./devops/actions/cached_checkout
       with:
         path: llvm
-        ref: ${{ inputs.build_ref || github.sha }}
+        ref: ${{ inputs.ref || github.sha }}
+        merge_ref: ${{ inputs.merge_ref }}
         cache_path: "D:\\\\github\\\\_work\\\\repo_cache\\\\"
     - name: Download compiler toolchain
       uses: actions/download-artifact@v4