[BE][8/N] Remove ShardedTensor from TP FSDP integration test and other tests depending on Sharded Linear (#96254)
We removed ShardedLinear in https://github.com/pytorch/pytorch/pull/95948 but it broke TP_FSDP integration test because it is using ShardedTensor in the test. Migrating using DTensor fixes the test. DTensor shards the bias too so that we need to change the test a little bit.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/96254
Approved by: https://github.com/huydhn
