* use warmup_ratio as a better default than warmup steps since it's data dependent * replace remainder of warmup_steps
* make pad_to_sequence_len default to the same value as sample_packing * remove duplicate validation * fix test * update description meta Co-authored-by: NanoCode012 <nano@axolotl.ai> --------- Co-authored-by: NanoCode012 <nano@axolotl.ai>