Update source-index-stage1.yml (#57435)

Again apply c842beb as the fix was overridden in the latest Arcade update.

Author: ViktorHofer

eng/common/templates/job/source-index-stage1.yml

@@ -35,20 +35,15 @@ jobs:
       packageType: sdk
       version: 3.1.x
 
-  - task: UseDotNet@2
-    displayName: Use .NET Core sdk
-    inputs:
-      useGlobalJson: true
-
+  - script: ${{ parameters.sourceIndexBuildCommand }}
+    displayName: Build Repository
+    
   - script: |
       dotnet tool install BinLogToSln --version $(SourceIndexPackageVersion) --add-source $(SourceIndexPackageSource) --tool-path .source-index/tools
       dotnet tool install UploadIndexStage1 --version $(SourceIndexPackageVersion) --add-source $(SourceIndexPackageSource) --tool-path .source-index/tools
       echo ##vso[task.prependpath]$(Build.SourcesDirectory)/.source-index/tools
     displayName: Download Tools
 
-  - script: ${{ parameters.sourceIndexBuildCommand }}
-    displayName: Build Repository
-
   - script: BinLogToSln -i $(BinlogPath) -r $(Build.SourcesDirectory) -n $(Build.Repository.Name) -o .source-index/stage1output
     displayName: Process Binlog into indexable sln
     env: