Search repo filter suggestions have incomplete regex

Created by: slimsag

Repo filter suggestions are currently in the form of <repo>$, e.g. gorilla/mux$ which means it can match multiple repositories e.g. deprecated-gorilla/mux would match. This is different from the repo: filter we provide on repo pages which starts with ^, i.e. repo:^gorilla/mux$ which correctly ensures it is matching the whole repo name and not a subset of it.