Is there an existing issue for this?

• I have searched the existing infra issues

Type of Request

bug

Infrastructure Environment

LUCI

What is happening?

Due to this change in mac_toolchain, Xcode install takes ~2 minutes longer for every build.

As a workaround we're hardcoding the mac_toolchain version to an older one, but we need a permanent solution.

Example:
On macOS 12, install xcode step takes 5.5s - https://luci-milo.appspot.com/ui/p/flutter/builders/staging/Mac_ios%20integration_ui_ios_driver_xcode_debug/1557/overview
With macOS 13, install xcode step takes 1.9m - https://luci-milo.appspot.com/ui/p/flutter/builders/staging/Mac_ios%20integration_ui_ios_driver_xcode_debug/1559/overview

Steps to reproduce

No response

Expected results

Xcode install takes less than 10 seconds when using from cache