Use PAT to increase the rate limit in ci pipeline (Azure#19409)

Co-authored-by: wyunchi-ms <[email protected]>

Author: wyunchi-ms

.azure-pipelines/util/analyze-steps.yml

@@ -49,13 +49,17 @@ steps:
     command: custom
     custom: msbuild
     arguments: 'build.proj /t:GenerateHelp /p:Configuration=${{ parameters.configuration }};PullRequestNumber=$(System.PullRequest.PullRequestNumber)'
+  env:
+      OCTOKITPAT: $(OCTOKITPAT)
 
 - task: DotNetCoreCLI@2
   displayName: 'Static Analysis'
   inputs:
     command: custom
     custom: msbuild
     arguments: 'build.proj /t:StaticAnalysis /p:Configuration=${{ parameters.configuration }};PullRequestNumber=$(System.PullRequest.PullRequestNumber)'
+  env:
+      OCTOKITPAT: $(OCTOKITPAT)
 
 - template: publish-artifacts-steps.yml
   parameters:

.azure-pipelines/util/build-steps.yml

@@ -49,6 +49,8 @@ steps:
     command: custom
     custom: msbuild
     arguments: 'build.proj /t:Build /p:Configuration=${{ parameters.configuration }};TestFramework=${{ parameters.testFramework }};PullRequestNumber=$(System.PullRequest.PullRequestNumber)'
+  env:
+      OCTOKITPAT: $(OCTOKITPAT)
 
 - task: PowerShell@2
   displayName: Build-AzPredictor

.azure-pipelines/util/test-steps.yml

@@ -36,6 +36,8 @@ steps:
     command: custom
     custom: msbuild
     arguments: 'build.proj /t:${{ parameters.testTarget }} /p:Configuration=${{ parameters.configuration }};TestFramework=${{ parameters.testFramework }};PullRequestNumber=$(System.PullRequest.PullRequestNumber)'
+  env:
+      OCTOKITPAT: $(OCTOKITPAT)
 
 - powershell: |
    Install-Module -Name Pester -RequiredVersion 4.10.1 -Force -SkipPublisherCheck

tools/BuildPackagesTask/Microsoft.Azure.Build.Tasks/FilesChangedTask.cs

@@ -100,12 +100,8 @@ public override bool Execute()
                 try
                 {
                     //The variable is set in pipeline: "azure-powershell - powershell-core"
-                    var token = Environment.GetEnvironmentVariable("NOSCOPEPAT_ADXSDKPS");
                     var client = new GitHubClient(new ProductHeaderValue("Azure"));
-                    if(RuntimeInformation.IsOSPlatform(OSPlatform.OSX) && !string.IsNullOrEmpty(token))
-                    {
-                        client.Credentials = new Credentials(token);
-                    }
+                    client.Credentials = new Credentials(Environment.GetEnvironmentVariable("OCTOKITPAT"));
                     var files = client.PullRequest.Files(RepositoryOwner, RepositoryName, int.Parse(PullRequestNumber))
                                     .ConfigureAwait(false).GetAwaiter().GetResult();
                     if (files == null)