Fabric: Remove designated initializers in ShadowNodeTest (#23714)
Fabric: Remove designated initializers in ShadowNodeTest (#23714)

Summary:
This pull request removes the designated initializers in `ShadowNodeTest.cpp`. This will help improve the portability of this file.

[General] [Fixed] - Removed designated initializers in `ShadowNodeTest`
Pull Request resolved: https://github.com/facebook/react-native/pull/23714

Differential Revision: D14305162

Pulled By: shergin

fbshipit-source-id: 81803652ece734a9b223d7a8b462a8b62cde7d1d

hammerandchisel/react-native,hoangpham95/react-native,myntra/react-native,exponentjs/react-native,janicduplessis/react-native,facebook/react-native,hammerandchisel/react-native,pandiaraj44/react-native,facebook/react-native,exponentjs/react-native,hoangpham95/react-native,pandiaraj44/react-native,arthuralee/react-native,pandiaraj44/react-native,janicduplessis/react-native,hoangpham95/react-native,facebook/react-native,javache/react-native,javache/react-native,hammerandchisel/react-native,janicduplessis/react-native,myntra/react-native,arthuralee/react-native,exponent/react-native,facebook/react-native,pandiaraj44/react-native,exponent/react-native,javache/react-native,hammerandchisel/react-native,hoangpham95/react-native,javache/react-native,exponent/react-native,pandiaraj44/react-native,javache/react-native,hammerandchisel/react-native,hammerandchisel/react-native,arthuralee/react-native,javache/react-native,janicduplessis/react-native,facebook/react-native,hammerandchisel/react-native,exponent/react-native,exponent/react-native,janicduplessis/react-native,exponentjs/react-native,myntra/react-native,exponent/react-native,pandiaraj44/react-native,myntra/react-native,facebook/react-native,hoangpham95/react-native,javache/react-native,hoangpham95/react-native,exponent/react-native,facebook/react-native,pandiaraj44/react-native,exponentjs/react-native,javache/react-native,janicduplessis/react-native,hoangpham95/react-native,myntra/react-native,myntra/react-native,exponent/react-native,javache/react-native,pandiaraj44/react-native,exponentjs/react-native,janicduplessis/react-native,facebook/react-native,facebook/react-native,myntra/react-native,arthuralee/react-native,myntra/react-native,myntra/react-native,exponentjs/react-native,hammerandchisel/react-native,exponentjs/react-native,janicduplessis/react-native,exponentjs/react-native,arthuralee/react-native,hoangpham95/react-native