Re-enabled disabled tests ReactPropForShadowNodeSpecTest and ReactPropForShadowNodeSetterTest

Summary:
X-link: facebook/yoga#1494

X-link: facebook/react-native#41788

Those tests are currently disabled due to Yoga attempting to do JNI calls.
I've added infra to bypass .so loading during tests, and we should be good to re-enable those tests by now.

Changelog:
[Internal] [Changed] - Re-enabled disabled tests ReactPropForShadowNodeSpecTest and ReactPropForShadowNodeSetterTest

Reviewed By: NickGerleman

Differential Revision: D51814491

fbshipit-source-id: adbbace19c94a0c6d8947f61221fafafd7797ac8

Author: cortinico

lib/yoga/src/main/java/com/facebook/yoga/YogaConfig.java

@@ -27,5 +27,5 @@ public abstract class YogaConfig {
 
   public abstract YogaLogger getLogger();
 
-  abstract long getNativePointer();
+  protected abstract long getNativePointer();
 }

lib/yoga/src/main/java/com/facebook/yoga/YogaConfigJNIBase.java

@@ -60,7 +60,7 @@ public YogaLogger getLogger() {
     return mLogger;
   }
 
-  long getNativePointer() {
+  protected long getNativePointer() {
     return mNativePointer;
   }
 }