LP#1945355 Inconsistent button placement: delete holdings dialog

LP#1945355 Inconsistent button placement: delete holdings dialog

The cancel button on the delete-volcopy-dialog now appears last
to be consistent with the eg-confirm dialogs.

To test:
1. set the ou setting "Alert on empty bib records" to true
2. delete the last copy on a record
3. note the Delete Holdings/OK and Cancel buttons are in the
   same order on the delete and confirmation dialogs

Signed-off-by: Dan Briem <dbriem@wlsmail.org>
Signed-off-by: Jennifer Weston <jennifer.weston@equinoxinitiative.org>
Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>