Removed unused code and linting fixes

Another bunch of gosec/golint related fixes

Remove method no longer used

protocol_common_poll.go

@@ -53,7 +53,15 @@ func (h *Headscale) handlePollCommon(
 		}
 
 		// update routes with peer information
-		h.EnableAutoApprovedRoutes(machine)
+		err = h.EnableAutoApprovedRoutes(machine)
+		if err != nil {
+			log.Error().
+				Caller().
+				Bool("noise", isNoise).
+				Str("machine", machine.Hostname).
+				Err(err).
+				Msg("Error running auto approved routes")
+		}
 	}
 
 	// From Tailscale client: