Call onRender inline instead of from startRenderCallbackIfNeeded (#51750)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/51750

changelog: [internal]

inline call `onRender()` instead of calling it from `startRenderCallbackIfNeeded`. This has identical functionality but allows to use Fantom to test C++ Animated. In Fantom, there is only one thread the existing mechanism in C++ Animated uses thread locals to capture which thread in the UI thread. Therefore, some assumptions are broken. This is just an easy workaround around the problem.

Reviewed By: javache, zeyap

Differential Revision: D75787084

fbshipit-source-id: 8d70ef2d13e4ab14807deb7ca4cb0844980f5901