Reduce the amount of traffic we get

Only connect to the non-paired devices when we're on discovery mode,
otherwise disconnect from them.

Reviewed by Albert Vaca

BUG: 352424

src/org/kde/kdeconnect/Device.java

@@ -798,4 +798,9 @@ public class Device implements BaseLink.PackageReceiver {
         pluginsChangedListeners.remove(listener);
     }
 
+    public void disconnect() {
+        for(BaseLink link : links) {
+            link.disconnect();
+        }
+    }
 }