Engine and Flutter using different xcode versions with the same cache
name is causing multiple problems when trying to find the runtimes. To
prevent this issue we will need to use different cache names for
different xcode versions.

Bug: https://github.com/flutter/flutter/issues/99429

This fixes a race condition in test/integration.shard/cache_test.dart which allowed the test to fail if the machine took a very long time to acquire a lock or launch a process.