Significant increase in import time for several sub-packages

It looks like there has been a significant (~40%) increase in import time for several sub-packages recently:

https://www.astropy.org/astropy-benchmarks/#imports.timeraw_import_astropy_coordinates

https://www.astropy.org/astropy-benchmarks/#imports.timeraw_import_astropy_nddata

asv seems to suggest that https://github.com/astropy/astropy/pull/9365 is the cause (cc @mhvk @eteq ).

Interestingly astropy.time also saw such an increase:

https://www.astropy.org/astropy-benchmarks/#imports.timeraw_import_astropy_time

but that was then fixed in https://github.com/astropy/astropy/pull/9491.

Start with the ASV import benchmarks for astropy.coordinates, astropy.nddata, and astropy.time, then compare the suspected changes in pull requests #9365 and #9491. Determine whether the roughly 40% regression remains and identify the relevant import-time change; done means the affected benchmark imports no longer show the regression.

Written by the indexing model from the issue text.