fix microbuild add service connection id.

Author: vseanreesermsft

eng/pipelines/jobs/prepare-signed-artifacts.yml

@@ -26,6 +26,7 @@ jobs:
       signType: $(SignType)
       zipSources: false
       feedSource: https://dnceng.pkgs.visualstudio.com/_packaging/MicroBuildToolset/nuget/v3/index.json
+      ConnectedPMEServiceName: 248d384a-b39b-46e3-8ad5-c2c210d5e7ca
     condition: and(succeeded(), in(variables['SignType'], 'real', 'test'))
   - task: DownloadBuildArtifacts@0
     displayName: Download IntermediateUnsignedArtifacts