Despite the definition sounding that way, I've run checks on a 1M hand database and a 5M hand database and not found any hands where the player cbet the turn and didn't bet the turn (ie- the raise of the donk counted as a cbet) - so it seems like the raise, cbet, face donk and raise doesn't count as a cbet. I also haven't found any hands where the player raised, cbet the flop, didn't cbet the turn, and cbet the river (which is the other option for getting a river cbet after raising a turn donk).
So tentatively I'd say that the turn donk breaks the chain. But I'm waiting for a query to come back on a 15M hand database and would like to try a few other tests before I say that for certain.
