Skip simulator install in official pack pipeline (dotnet#34802)

Backport of dotnet#34801 to main.

The official pack pipeline doesn't need iOS simulators — it only builds
and packs NuGet packages. The simulator install step is timing out on
macOS agents, blocking BAR build production.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 3 people

eng/pipelines/ci-official.yml

@@ -104,6 +104,7 @@ extends:
             onlyAndroidPlatformDefaultApis: true
             skipAndroidEmulatorImages: true
             skipAndroidCreateAvds: true
+            skipSimulatorSetup: true
             skipProvisioning: true
             skipXcode: false
             base64Encode: true