use the heartbeat interval for slack time

gossipsub.go

@@ -118,10 +118,6 @@ var (
 	// before attempting to re-graft.
 	GossipSubPruneBackoff = time.Minute
 
-	// GossipSubPruneBackoffSlack is the slack time after expiry of a backoff and before
-	// attempting a GRAFT.
-	GossipSubPruneBackoffSlack = time.Second
-
 	// GossipSubConnectors controls the number of active connection attempts for peers obtained through PX.
 	GossipSubConnectors = 8
 
@@ -1501,7 +1497,7 @@ func (gs *GossipSubRouter) clearBackoff() {
 		return
 	}
 
-	now := time.Now().Add(GossipSubPruneBackoffSlack)
+	now := time.Now().Add(2 * GossipSubHeartbeatInterval)
 	for topic, backoff := range gs.backoff {
 		for p, expire := range backoff {
 			if expire.Before(now) {