TEENAGENT: Add missing "break"s to switch cases

I think this is the correct thing to do, and that it won't have
any noticeable effect whatsoever.

Cases 29 and 30 happen in the first half of the game, in the
cantine, while case 42 happens in the second half of the game. By
the time you reach the point where case 42 does something, I don't
think it's possible to get back to cases 29 and 30, so when case
29 falls through neither 30 nor 42 will do anything.

CID 1003730, 1003731