Centralized executor

core/src/mindustry/net/Net.java

@@ -33,7 +33,7 @@ public class Net{
     private final ObjectMap<Class<?>, Cons> clientListeners = new ObjectMap<>();
     private final ObjectMap<Class<?>, Cons2<NetConnection, Object>> serverListeners = new ObjectMap<>();
     private final IntMap<StreamBuilder> streams = new IntMap<>();
-    private final ExecutorService pingExecutor = Threads.cachedExecutor();
+    private final ExecutorService pingExecutor = Threads.unboundedExecutor();
 
     private final NetProvider provider;