[ci] Allow to set the agents for template build (dotnet#23849)

eng/pipelines/handlers.yml

@@ -87,6 +87,18 @@ parameters:
  vmImage: $(macOSXVmImage)
  artifact: nuget-macos
 
+ - name: BuilTemplatePlatforms
+ type: object
+ default:
+ - name: Windows
+ poolName: $(windowsVmPool)
+ vmImage: $(windowsVmImage)
+ artifact: build-windows
+ - name: macOS
+ poolName: $(macOSXVmPool)
+ vmImage: $(macOSXVmImage)
+ artifact: build-macos
+
  - name: RunTemplatePlatforms
  type: object
  default:
@@ -277,7 +289,7 @@ stages:
  - template: common/maui-templates.yml
  parameters:
  RunPlatforms: ${{ parameters.RunTemplatePlatforms }}
- BuildPlatforms: ${{ parameters.BuildPlatforms }}
+ BuildPlatforms: ${{ parameters.BuilTemplatePlatforms }}
 
  # - ${{ if eq(variables['System.TeamProject'], 'devdiv') }}:
  # - template: common/localization-handoff.yml # Process outgoing strings [Localization Handoff]