LP1999304 (follow-up): blank alt text for decorative image

LP1999304 (follow-up): blank alt text for decorative image

Steps to test:
1. Search the staff catalog for Ready Player One in the concerto dataset.
2. Check the Group Formats/Editions checkbox
3. Press the Place hold button
4. Use your browser's dev tools (or a screen reader) to find the accessible
name of the Large Print Book checkbox.
5. Confirm that the accessible name is Large Print Book, rather than
Large Print Book Large Print Book.

Signed-off-by: Jane Sandberg <sandbergja@gmail.com>