test(channelserver): reduce polling interval from 10ms to 1ms

LoopDelay is 0 in test servers (bare struct, no Viper defaults), so
sendLoop spins without delay and satisfies conditions in <1ms. The
10ms poll interval was the new bottleneck — dropping to 1ms cuts the
channelserver test suite from ~136s to ~5s.

server/channelserver/sys_channel_server_test.go

@@ -291,7 +291,7 @@ func TestBroadcastMHFAllSessions(t *testing.T) {
 		if receivedCount == sessionCount {
 			break
 		}
-		time.Sleep(10 * time.Millisecond)
+		time.Sleep(1 * time.Millisecond)
 	}
 
 	// Stop all sessions