Fix device cleanup

Summary: Found some code duplication causing old devices not entirely to be cleaned up as they should

Reviewed By: nikoant

Differential Revision: D26422665

fbshipit-source-id: f57757f7260ac5de17edd80e9f66cc844d1a6213

desktop/app/src/devices/BaseDevice.tsx

@@ -126,12 +126,6 @@ export default class BaseDevice {
     };
   }
 
-  teardown() {
-    for (const instance of this.sandyPluginStates.values()) {
-      instance.destroy();
-    }
-  }
-
   addLogListener(callback: DeviceLogListener): Symbol {
     const id = Symbol();
     this.logListeners.set(id, callback);