Update BERT yamls for compatibility with main branch

[jacobfulano]

• Update BERT mcloud yamls to include precision amp_bf16. This is a minor PR that changes 2 lines of code for compatibility
• Update mcli yamls to be compatible with the folder structure in the main branch

  cd examples/examples/benchmarks/bert
  pip install -r requirements.txt
  python src/convert_dataset.py --dataset c4 --data_subset en --out_root ./my-copy-c4 --splits train_small val