[Profiler] Fix memory profile type from recent refactor (#71417)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71417
I accidentally changed CPU_INSTANT_EVENT to CPU_OP, which broke TensorBoard.
Test Plan: Make memory profiling unit test check this case.
Reviewed By: aaronenyeshi
Differential Revision: D33637286
fbshipit-source-id: c95945f6b85cd4168820bd4d2a9203274a0a5bd6
(cherry picked from commit b1e258672af4b83d824b8c8eb565af0ffdfa895b)
