Fix docker images BoM/CVE scan

Signed-off-by: ZePan110 <ze.pan@intel.com>

Author: ZePan110

.github/workflows/manual-docker-scan.yml

@@ -47,7 +47,7 @@ jobs:
   scan-docker:
     needs: get-image-list
     runs-on: "docker-build-${{ inputs.node }}"
-    if: ${{ fromJSON(needs.get-image-list.outputs.matrix).length != 0 }}
+    if: ${{ needs.get-image-list.outputs.matrix != '' }}
     strategy:
       matrix:
         image: ${{ fromJson(needs.get-image-list.outputs.matrix) }}