Add code owner file in sparse checkout (Azure#21862)

Author: sima-zhu

eng/pipelines/templates/stages/archetype-python-release.yml

@@ -162,6 +162,7 @@ stages:
                               SkipDefaultCheckout: true
                               Paths:
                                 - sdk/**/*.md
+                                - .github/CODEOWNERS
                           - download: current
                           - template: /eng/common/pipelines/templates/steps/update-docsms-metadata.yml
                             parameters:
@@ -270,6 +271,7 @@ stages:
             SkipDefaultCheckout: true 
             Paths:
               - sdk/**/*.md
+              - .github/CODEOWNERS
         - download: current
         - pwsh: |
             Get-ChildItem -Recurse $(Pipeline.Workspace)/${{parameters.ArtifactName}}/