golink: use http.StatusFound for redirects

If users belong to multiple tailnets with golinks deployed (as is common) then
permanent redirects for one will conflict with the others. To prevent this we
will use `http.StatusFound` to prompt browsers to continue to visit the `go/`
URL in the future.

Signed-off-by: Patrick O'Doherty <patrick@tailscale.com>

Author: patrickod

golink.go

@@ -329,7 +329,7 @@ func deleteLinkStats(link *Link) {
 // requests. It redirects all requests to the HTTPs version of the same URL.
 func redirectHandler(hostname string) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		http.Redirect(w, r, (&url.URL{Scheme: "https", Host: hostname, Path: r.URL.Path}).String(), http.StatusMovedPermanently)
+		http.Redirect(w, r, (&url.URL{Scheme: "https", Host: hostname, Path: r.URL.Path}).String(), http.StatusFound)
 	})
 }