Deactivate non pluggable discoverers

Author: facchinm

arduino-core/src/cc/arduino/packages/DiscoveryManager.java

@@ -57,8 +57,8 @@ public DiscoveryManager(Map<String, TargetPackage> packages) {
 //    this.packages = packages;
 
     discoverers = new ArrayList<>();
-    discoverers.add(serialDiscoverer);
-    discoverers.add(networkDiscoverer);
+    //discoverers.add(serialDiscoverer);
+    //discoverers.add(networkDiscoverer);
 
     // Search for discoveries in installed packages
     for (TargetPackage targetPackage : packages.values()) {