Bug 25016: Coce should not return a 1-pixel Amazon cover image

Bug 25016: Coce should not return a 1-pixel Amazon cover image

This patch adds an onload function to the JavaScript which loads images
from Coce. In the case where the image is 1 x 1 pixel the image should
be removed.

To test you should have Coce enabled and Amazon.com included in the list
of sources.

 - Apply the patch and view the bibliographic details page under a
  variety of conditions:
   - A title which has a matching Amazon image:
     - The image should load as expected.
   - A title which doesn't have a matching Amazon image
     - The image should not be found in the source at all after the page
       has loaded.
  - Test with local cover images enabled

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>