[Profiler] Regularize `AccumulateGrad` name (#86909)
Memory profiler will use AccumulateGrad when detecting gradients. The name difference between Windows and other platforms has already cropped up with profiler trees so it makes sense to address it at the source.
Differential Revision: [D40347550](https://our.internmc.facebook.com/intern/diff/D40347550/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86909
Approved by: https://github.com/slgong-fb, https://github.com/aaronenyeshi
