Pandas REF: dtype_backend argument in sql module mixes lib.no_default and numpy

See conversation at https://github.com/pandas-dev/pandas/pull/60324#discussion_r1843969801 - we should change the internal methods to all use lib.no_default

Comment From: Harshachelva

Take

Comment From: Harshachelva

@WillAyd does it mean we remove the backward compatibility for dtype_backend=="numpy"