[profiler] Fix time discrepancy between legacy and kineto events (#55226)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55226
Fixes a bug caused by using different clocks in legacy events, also fixes two
small issues with not using relative time in memory events and discrepancy
between start and stop profile events CUDA-wise
Test Plan: CI
Reviewed By: xuzhao9
Differential Revision: D27534920
fbshipit-source-id: 7a877367b3031660516c9c4fdda1bf47e77bcb3e
