Created by: suchenzang
Continuing to break down https://github.com/facebookresearch/metaseq/pull/197
(Base branch will switch/be rebased to main once https://github.com/facebookresearch/metaseq/pull/251 is merged)
Removing Adam8bit and stable-emb/block-wise flags which were brought in together in https://github.com/fairinternal/fairseq-py/pull/2063 .