Use multi-line if conditionals, more readable, and restore default 0.

Author: jonsimantov

.github/workflows/cpp-packaging.yml

@@ -10,6 +10,7 @@ on:
         description: 'commit ID to package'
       preserveIntermediateArtifacts:
         description: 'preserve intermediate artifacts?'
+        default: 0
       downloadPublicVersion:
         description: 'public version # to test against'
       downloadPreviousRun:
@@ -43,8 +44,15 @@ jobs:
               echo "::warning ::Using commit ID '${{ github.event.inputs.commitIdToPackage }}' for building and packaging SDK and tests."
             fi
           fi
+
       - name: log if preserving intermediate artifacts
-        if: ${{ !(github.event.inputs.preserveIntermediateArtifacts == 0) }}
+        # Inverse of the conditional on the cleanup_artifacts step.
+        if: |
+          !(
+            (github.event.inputs.preserveIntermediateArtifacts == 0 || github.event.inputs.preserveIntermediateArtifacts == '')
+            && github.event.inputs.downloadPublicVersion == ''
+            && github.event.inputs.downloadPreviousRun == ''
+          )
         run: echo "::warning ::Intermediate artifacts will be preserved."
 
   build_tools:
@@ -539,7 +547,12 @@ jobs:
     name: cleanup-artifacts
     runs-on: ubuntu-latest
     needs: [merge_packages]
-    if: ${{ (github.event.inputs.preserveIntermediateArtifacts == 0 || github.event.inputs.preserveIntermediateArtifacts == '') && github.event.inputs.downloadPublicVersion == '' && github.event.inputs.downloadPreviousRun == '' }}
+    if: |
+      (
+        (github.event.inputs.preserveIntermediateArtifacts == 0 || github.event.inputs.preserveIntermediateArtifacts == '')
+        && github.event.inputs.downloadPublicVersion == ''
+        && github.event.inputs.downloadPreviousRun == ''
+      )
     steps:
     - uses: geekyeggo/delete-artifact@v1
       with: