In the Annotatable XBlock, the <instructions> element was appearing
twice in the student view:
* Once in "annotatable-instructions" (where it should be).
* Again in "annotatable-content" (where annotations and other content are rendered).
The _render_content method processed and rendered the entire XML
data, including <instructions>, without removing it. The
_extract_instructions method, which is responsible for removing
<instructions>, was not called in _render_content, leading to
duplication.
This fix will:
* Prevents duplicate instructions in the student view.
* Maintains the expected behavior of showing instructions only in
"annotatable-instructions".
* No impact on existing annotation functionality.
