Bug 16020 - Remove unused CSS and images following label creator UX changes

Bug 16020 - Remove unused CSS and images following label creator UX changes

Since the changes made by Bug 16020, some CSS and images are no longer
needed by the label and patron card creator modules. This patch removes
the unnecessary files and CSS.

To test, apply the patch and go to Tools -> Label creator.

- Confirm that the label creator home page doesn't look broken.
- Go to Tools -> Patron card creator and confirm that the page doesn't
  look broken.
- Search Koha files for references to label-creator-image.png. There
  should be none.

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com