Remove useVanillaJNI flag and usage of fbjni in yoga build

Summary:
## Changelog:

[General] [Yoga] - Use vanilla jni instead of fbjni for all the jni communication

Reviewed By: astreet

Differential Revision: D17808005

fbshipit-source-id: 5e9a1ed73978f519c71c248774a28e5a294e7c7f

java/tests/com/facebook/yoga/TestParametrization.java

@@ -28,25 +28,7 @@ public class TestParametrization {
         return "JNI";
       }
     };
-
-    NodeFactory nodeFactoryUsingVanillaJNI = new NodeFactory() {
-      @Override
-      public YogaNode create() {
-        return YogaNodeFactory.create(true);
-      }
-
-      @Override
-      public YogaNode create(YogaConfig config) {
-        config.setUseVanillaJNI(true);
-        return YogaNodeFactory.create(config);
-      }
-
-      @Override
-      public String toString() {
-        return "VanillaJNI";
-      }
-    };
-    return Arrays.asList(nodeFactory, nodeFactoryUsingVanillaJNI);
+    return Arrays.asList(nodeFactory);
   }