Rename shard_lengths to shard_sizes to be more inline with Tensor sizes. (#66464)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66464
Dimension sizes are referred to as `size` in general in PyTorch and
hence rename shard_lengths to shard_sizes.
#Closes: https://github.com/pytorch/pytorch/issues/65794
ghstack-source-id: 143866449
Test Plan: waitforbuildbot
Reviewed By: fduwjj, wanchaol
Differential Revision: D31564153
fbshipit-source-id: 6273426c4b0e079358806070d0d9644740adb257
