ci: remove xcode switch step

Refs 480888c7ce

build/azure-pipelines/darwin/product-build-darwin.yml

@@ -37,12 +37,6 @@ steps:
       git config user.name "VSCode"
     displayName: Prepare tooling
 
-  - script: |
-      set -e
-      sudo xcode-select -s /Applications/Xcode_12.2.app
-    displayName: Switch to Xcode 12
-    condition: and(succeeded(), eq(variables['VSCODE_ARCH'], 'arm64'))
-
   - script: |
       set -e
       git pull --no-rebase https://github.com/$(VSCODE_MIXIN_REPO).git $(node -p "require('./package.json').distro")