Fix early return bug and improve test quality per maintainer feedback

- Remove early return in hydrateProperties() that was skipping text content validation
- Convert all React.createElement() to JSX syntax for better readability
- Replace eventLog arrays with jest.fn() mocks for proper testing
- Use querySelector() instead of firstChild for robust element selection
- Remove hydration warning suppression to catch regressions
- Fix hasAttribute/getAttribute assertion pattern
- Rename ce-not-registered to ce-registered-after-hydration for clarity
- Improve act() usage pattern with hydrateRoot

All 9 tests passing.

Author: Omcodes23

packages/react-dom-bindings/src/client/ReactDOMComponent.js

@@ -3231,7 +3231,7 @@ export function hydrateProperties(
         undefined,
       );
     }
-    return true;
+    // Don't return early - let it continue to text content validation below
   }
 
   const children = props.children;