import_cldr: further DRY out draft/alt skipping
import_cldr: further DRY out draft/alt skipping

Thanks for the idea, @jtwang!

srisankethu/babel,python-babel/babel,iamshubh22/babel,iamshubh22/babel,srisankethu/babel,mitsuhiko/babel,python-babel/babel,iamshubh22/babel,srisankethu/babel,mitsuhiko/babel,mitsuhiko/babel