[Sanitizers][Driverkit] Stop using Sanitizer Allocator64 on Driverkit

Before refactoring this code, all arm64 were set to use the 32bit allocator. This patch reverts back that behavior for DriverKit.

Because we target DriverKit as the target OS, rather than a specific platform, reverting back to the previous behavior is preferred to fix a failure we are seeing on embedded platforms.
Though it may be more correct in the future to match the allocator to the platform being used.

rdar://113649286

Differential Revision: https://reviews.llvm.org/D158028