NEON surface datasets are defined in two places -- should just be one in namelist_defaults_ctsm.xml

I noticed that the NEON surface datasets are defined both in namelist_defaults as well as in the defaults NEON user mod directory. For code maintenance this should be only in one place and it should be namelist defaults alongside all other surface datasets. This allows updates to surface datasets to just be in one place rather than multiple places.

Definition of done:
- [x] Do this for NEON
- [ ] Do this for PLUMBER2