Remove get-github-token-steps.yml (Azure#26660)

* Update code-gen.yml

* Delete .azure-pipelines/util/get-github-token-steps.yml

Author: YanaXu

.azure-pipelines/code-gen.yml

@@ -21,8 +21,7 @@ jobs:
   pool: pool-windows-2019
   steps:
   - checkout: self
-    persistCredentials: true
-  - template: util/get-github-token-steps.yml
+  - template: util/get-github-pat-steps.yml
   - task: NodeTool@0
     displayName: Use Node 14.15.5
     inputs: