disable two more tasks to fix the failures

.ci/azure-pipelines-abi.yml

@@ -62,6 +62,7 @@ jobs:
 
       - task: DownloadPipelineArtifact@2
         displayName: 'Download Reference Assembly Build Artifact'
+        enabled: false
         inputs:
           source: "specific"
           artifact: "$(NugetPackageName)"
@@ -73,6 +74,7 @@ jobs:
 
       - task: CopyFiles@2
         displayName: 'Copy Reference Assembly Build Artifact'
+        enabled: false
         inputs:
           sourceFolder: $(System.ArtifactsDirectory)/current-artifacts
           contents: '**/*.dll'