create PR only after codes and samples are generated

- expand the steps of generating codes and samples, move PR creation into a separate job which is executed only after success codes/sample generation
- remove `-f` for git push
- change push branch to have version as name suffix to avoid potential conflict

Author: archerzz

eng/pipelines/build.yml

@@ -179,15 +179,13 @@ stages:
               failOnStderr: false
               workingDirectory: $(Build.SourcesDirectory)/autorest.csharp
               displayName: 'Update SDK codes and generator version in Azure SDK repo'
-            - template: /eng/common/pipelines/templates/steps/create-pull-request.yml@azure-sdk-tools
+            - template: /eng/common/pipelines/templates/steps/git-push-changes.yml@azure-sdk-tools
               parameters:
-                BaseBranchName: main
-                RepoName: azure-sdk-for-net
-                PRBranchName: auto-update-autorest
+                BaseRepoBranch: auto-update-autorest-$(AutorestCSharpVersion)
+                BaseRepoOwner: azure-sdk
                 CommitMsg: Update AutoRest C# version to $(AutorestCSharpVersion)
-                PRBody: Update AutoRest C# version to $(AutorestCSharpVersion)
-                PRTitle:  Update AutoRest C# version
-                PushArgs: -f
+                TargetRepoOwner: Azure
+                TargetRepoName: $(Build.Repository.Name)
                 WorkingDirectory: $(Build.SourcesDirectory)/azure-sdk-for-net
                 ScriptDirectory: $(Build.SourcesDirectory)/azure-sdk-tools/eng/common/scripts
         - job: Update_Samples
@@ -210,14 +208,37 @@ stages:
               failOnStderr: false
               workingDirectory: $(Build.SourcesDirectory)/autorest.csharp
               displayName: 'Update sample codes and generator version in Azure SDK repo'
-            - template: /eng/common/pipelines/templates/steps/create-pull-request.yml@azure-sdk-tools
+            - template: /eng/common/pipelines/templates/steps/git-push-changes.yml@azure-sdk-tools
               parameters:
-                BaseBranchName: main
-                RepoName: azure-sdk-for-net
-                PRBranchName: auto-update-autorest
+                BaseRepoBranch: auto-update-autorest-$(AutorestCSharpVersion)
+                BaseRepoOwner: azure-sdk
                 CommitMsg: Update AutoRest C# version to $(AutorestCSharpVersion)
-                PRBody: Update AutoRest C# version to $(AutorestCSharpVersion)
-                PRTitle:  Update AutoRest C# version
-                PushArgs: -f
+                TargetRepoOwner: Azure
+                TargetRepoName: $(Build.Repository.Name)
                 WorkingDirectory: $(Build.SourcesDirectory)/azure-sdk-for-net
                 ScriptDirectory: $(Build.SourcesDirectory)/azure-sdk-tools/eng/common/scripts
+        - job: Create_PR
+          dependsOn:
+            - Update_Codes
+            - Update_Samples
+          variables:
+            AutorestCSharpVersion: $[stageDependencies.Build_and_Test.Build.outputs['Package.AutorestCSharpVersion']]
+            CadlEmitterVersion: $[stageDependencies.Build_and_Test.Build.outputs['Publish.CadlEmitterVersion']]
+          steps:
+            - checkout: self
+            - checkout: azure-sdk-tools
+            - task: PowerShell@2
+              displayName: Create pull request
+              condition: and(succeeded(), eq(variables['HasChanges'], 'true'))
+              inputs:
+                pwsh: true
+                filePath: $(Build.SourcesDirectory)/azure-sdk-tools/eng/common/scripts/Submit-PullRequest.ps1
+                arguments: >
+                  -RepoOwner "Azure"
+                  -RepoName "$(RepoNameWithoutOwner)"
+                  -BaseBranch "main"
+                  -PROwner "azure-sdk"
+                  -PRBranch "auto-update-autorest-$(AutorestCSharpVersion)"
+                  -AuthToken "$(azuresdk-github-pat)"
+                  -PRTitle "Update AutoRest C# version"
+                  -PRBody "$Update AutoRest C# version to $(AutorestCSharpVersion)"