Sync eng/common directory with azure-sdk-tools for PR 11336 (#6668)

* Install .NET from tools repo global.json

* Set workingDirectory to tools root

* use exact same install steps as tools repo

* revert formatting

* formatting

---------

Co-authored-by: Mike Harder <mharder@microsoft.com>

eng/common/pipelines/templates/jobs/perf.yml

@@ -112,8 +112,29 @@ jobs:
   - template: /eng/common/pipelines/templates/steps/verify-agent-os.yml
     parameters:
       AgentImage: $(OSVmImage)
-      
-  - template: /eng/pipelines/templates/steps/install-dotnet.yml
+
+  # Copied from eng/pipelines/templates/steps/install-dotnet.yml, but changed workingDirectory
+  - task: UseDotNet@2 # About UseDotNet@2 task: https://learn.microsoft.com/azure/devops/pipelines/tasks/reference/use-dotnet-v2?view=azure-pipelines
+    displayName: "Use .NET SDK from global.json"
+    retryCountOnTaskFailure: 3
+    inputs:
+      useGlobalJson: true
+      workingDirectory: azure-sdk-tools
+
+  # Copied from eng/pipelines/templates/steps/install-dotnet.yml, but changed workingDirectory
+  - task: UseDotNet@2
+    displayName: "Use .NET SDK 8.0.x"
+    retryCountOnTaskFailure: 3
+    inputs:
+      # We must install sdk, not just runtime, as it is required by some of our tools, like test-proxy.
+      # Specifically, test-proxy requires asp.net core runtime, which is installed only when sdk option
+      # is selected, per: https://github.com/microsoft/azure-pipelines-tasks/issues/14405
+      packageType: sdk
+      version: 8.0.x
+      # performMultiLevelLookup comes into play when given .NET executable target runtime is different
+      # than the installed .NET SDK. Without this, such runtime would not be found.
+      performMultiLevelLookup: true
+      workingDirectory: azure-sdk-tools
 
   - ${{ parameters.InstallLanguageSteps }}