fix xr read section in access nb / read_s3 fn

[e-marshall]

with xr version 2025.1.2 , don't need to pass storage options, engine to xr.open_dataset(). Need to:

• Update text section in access nb to reflect this

• Probably means read_in_s3() fn isn't necessary. This will need to be updated in all notebooks, espec. New velocity #2.