Fix resource pipeline name

Author: premun

eng/source-build-pre-release-8.0.yml

@@ -8,7 +8,7 @@ pool:
 resources:
   pipelines:
   - pipeline: dotnet-staging-pipeline-resource
-    source: Stage-DotNet-Test
+    source: Stage-DotNet
 
 parameters:
 - name: useSpecificPipelineRunIDs