bug 15112: Make greybox consistent size across label/card creator

bug 15112: Make greybox consistent size across label/card creator

Also fixes minor issue with buttons stacking on patroncards/edit-batch
and labels/label-manage

To test:

Export a batch every way you can:

multiple together from label/label-manage
individual items from labels/label-edit-batch
selected items from labels/label-edit-batch
export full batch from labels/label-edit-batch

multiple together from patroncards/manage
individual cards from patroncards/manage
individual cards from patroncards/edit-batch
selected cards from patroncards/edit-batch
export full batch from patroncards/edit-batch

Also notice that before this patch, the delete and export buttons
were stacking on the table rows, and  that now they are not doing
that anymore. It may take a force refresh to see the behaviour and
the change.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>