[ci] premerge: upload artifacts even on failure (llvm#147999)

This makes sure we upload the artifacts even if the previous step
failed.

This is helpful because we wish to upload crash reproducers, which the
scritps are already prepared to do.

Example:
https://github.com/llvm/llvm-project/actions/runs/16180778101/job/45676677544?pr=147835

Author: mizvekov

.github/workflows/premerge.yaml

@@ -63,6 +63,7 @@ jobs:
 
           ./.ci/monolithic-linux.sh "${projects_to_build}" "${project_check_targets}" "${runtimes_to_build}" "${runtimes_check_targets}" "${runtimes_check_targets_needs_reconfig}"
       - name: Upload Artifacts
+        if: '!cancelled()'
         uses: actions/upload-artifact@65c4c4a1ddee5b72f698fdd19549f0f0fb45cf08 # v4.6.0
         with:
           name: Premerge Artifacts (Linux)
@@ -113,6 +114,7 @@ jobs:
           call C:\\BuildTools\\Common7\\Tools\\VsDevCmd.bat -arch=amd64 -host_arch=amd64
           bash .ci/monolithic-windows.sh "${{ steps.vars.outputs.windows-projects }}" "${{ steps.vars.outputs.windows-check-targets }}"
       - name: Upload Artifacts
+        if: '!cancelled()'
         uses: actions/upload-artifact@65c4c4a1ddee5b72f698fdd19549f0f0fb45cf08 # v4.6.0
         with:
           name: Premerge Artifacts (Windows)