Remove sketchy-null lint disable (DOMRectReadOnly.js) (#59763)

Summary:

Drop `sketchy-null:off` from the file-level `flowlint` directive in `DOMRectReadOnly.js`, keeping `unsafe-getters-setters:off`. No code in the file triggers a sketchy-null lint (Flow reports nothing with the disable removed), so only the directive changes and runtime behavior is identical.

Changelog: [Internal]

Differential Revision: D128806044

Pull Request resolved: #59763

Author: jcperez-ch

packages/react-native/src/private/webapis/geometry/DOMRectReadOnly.js

@@ -16,7 +16,7 @@
 
 import {setPlatformObject} from '../webidl/PlatformObjects';
 
-// flowlint sketchy-null:off, unsafe-getters-setters:off
+// flowlint unsafe-getters-setters:off
 
 export interface DOMRectInit {
   x?: ?number;