[RNMobile] Fix replacing empty paragraph in inner block (#20653)

* Check if the replaceable block is a nested one

packages/block-editor/src/components/inserter/menu.native.js

@@ -241,7 +241,8 @@ export default compose(
  );
 
  const count = getBlockCount();
- if ( count === 1 ) {
+ // Check if there is a rootClientId because that means it is a nested replacable block and we don't want to clear/reset all blocks.
+ if ( count === 1 && ! ownProps.rootClientId ) {
  // removing the last block is not possible with `removeBlock` action
  // it always inserts a default block if the last of the blocks have been removed
  clearSelectedBlock();