Replace last React.Ref type usage in react-native (#46931)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/46931

Prepare for deletion of this deprecated type that contain support for string ref in the next flow release.

Changelog: [Internal]

Reviewed By: rshest

Differential Revision: D64127228

fbshipit-source-id: 9d3a1c0e6303efb35a540349fdc8e42b7b70be8b

packages/react-native/Libraries/Image/ImageProps.js

@@ -20,7 +20,7 @@ import type {
 import type {LayoutEvent, SyntheticEvent} from '../Types/CoreEventTypes';
 import typeof Image from './Image';
 import type {ImageSource} from './ImageSource';
-import type {Node, Ref} from 'react';
+import type {ElementRef, Node, RefSetter} from 'react';
 
 export type ImageLoadEvent = SyntheticEvent<
   $ReadOnly<{|
@@ -291,5 +291,5 @@ export type ImageBackgroundProps = $ReadOnly<{|
    *
    * See https://reactnative.dev/docs/imagebackground#imageref
    */
-  imageRef?: Ref<Image>,
+  imageRef?: RefSetter<ElementRef<Image>>,
 |}>;

packages/react-native/Libraries/__tests__/__snapshots__/public-api-test.js.snap

@@ -4880,7 +4880,7 @@ export type ImageBackgroundProps = $ReadOnly<{|
   children?: Node,
   style?: ?ViewStyleProp,
   imageStyle?: ?ImageStyleProp,
-  imageRef?: Ref<Image>,
+  imageRef?: RefSetter<ElementRef<Image>>,
 |}>;
 "
 `;