Merge pull request #43171 from dotnet/dev/dibarbet/dont_publish

Don't publish assets to myget during PR validation

azure-pipelines-official.yml

@@ -123,7 +123,7 @@ stages:
       inputs:
         filePath: 'eng\publish-assets.ps1'
         arguments: '-configuration $(BuildConfiguration) -branchName "$(SourceBranchName)" -mygetApiKey $(Roslyn.MyGetApiKey) -nugetApiKey $(Roslyn.NuGetApiKey) -gitHubUserName $(Roslyn.GitHubUserName) -gitHubToken $(Roslyn.GitHubToken) -gitHubEmail $(Roslyn.GitHubEmail)'
-      condition: succeeded()
+      condition: and(succeeded(), eq(variables['PRNumber'], 'default'))
 
     # Publish OptProf configuration files
     - task: ms-vscs-artifact.build-tasks.artifactDropTask-1.artifactDropTask@0