Bug 31137: Only display label printer profiles when editing labels

Bug 31137: Only display label printer profiles when editing labels

This patch filters the printer profiles in the label edition template so you may only choose Printer Profiles created for Labels.

To test
1 Create a new Printer Profile in Patron Cards
2 Edit a Label template, pick the Printer Profile you just created.
3 Save the Label Template. You get an error 500
4 apply patch, restart services
5 Edit a Label template and check that you can't pick the Printer Profile you created in Patron Cards

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>