This is an American colloquialism for a retirement home, which has been in American English for the last twenty years and which we seem to have recently adopted. I was puzzled by it but found that the use of raisin is with reference to the wrinkles on the faces of the inhabitants.
I think this is an instance of an Australian TV scriptwriter pulling in an Americanism as a bit of colloquial bling. I don’t think it has any frequency in Australian English. That said, given the growing number of retirement villages and the growing interest we have in them, the number of ways of referring to them may well increase.