Fix Hard Fault in arm_executor_runner (#5302)

Summary:
The introduction of the PlatformMemoryAllocator in https://github.com/pytorch/executorch/pull/5121 introduced a hard fault in arm_executor_runner when not supplying the temp_allocator in the MemoryManager, so add it to get tests running again.

Change-Id: I357244a15c1b1fdee567ad828e09e3607e43e2e7

Pull Request resolved: https://github.com/pytorch/executorch/pull/5302

Reviewed By: manuelcandales

Differential Revision: D62582281

Pulled By: digantdesai

fbshipit-source-id: c650771d5ad2eddf80b30fcbafaf6e731ca9eed3