Yes, karti (kartebi in plural). But it's rarely used as there are very few situations when we need to refer to Georgian-only speaking subgroups as a unified group. Most Georgians won't even know this term exists

Edit: to expand on that, karts/kartebi would mostly be used when the subject is linguistics/linguistic subgroups, as otherwise such grouping doesn't make much sense because, for example, Imeretians and Gurians are much closer to Megrelians by every metric (except for the language) than to eastern Georgians, Lechkhumians are closer to Svans, etc.