Revert "discovery: add new option to toggle gossip rate limiting"

This reverts commit 13a2598ded.

server.go

@@ -819,7 +819,6 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 		MinimumBatchSize:        10,
 		SubBatchDelay:           time.Second * 5,
 		IgnoreHistoricalFilters: cfg.IgnoreHistoricalGossipFilters,
-		GossipUpdateThrottle:    !cfg.ProtocolOptions.NoGossipThrottle(),
 		PinnedSyncers:           cfg.Gossip.PinnedSyncers,
 	},
 		s.identityECDH.PubKey(),