> magic eyeballs

https://en.wikipedia.org/wiki/Happy_Eyeballs is the usual name. It's not quite identical, since you often want to give your preferred transport a nominal headstart so it usually succeeds. But yes, there are some similarities -- you race during connection setup so that you don't have to wait for a connection timeout (on the order of seconds) if the preferred mechanism doesn't work for some reason.

The main term I've seen for this particular approach is "request hedging" (https://grpc.io/docs/guides/request-hedging/, which links to the paper by Dean and Barroso).