test_fsdp_pure_fp16.py has been mostly flaky or broken. For now, we are disabling the parameter check after the training step. However, this means that the backward pass could be incorrect for pure FP16 models using FSDP.

cc @mrshenli @pritamdamania87 @zhaojuanmao @satgera @rohan-varma @gqchen @aazzolini @osalpekar @jiayisuse @H-Huang @kwen2501