Bug 12604: refactoring Category.t with TestBuilder

Bug 12604: refactoring Category.t with TestBuilder

The tests have been refactored with the module TestBuilder.

Test plan:
1/ Apply the patch 12603
2/ The command : prove t/db_dependent/Category.t has to be a success without error or warning :
t/db_dependent/Category.t .. ok
All tests successful.
Files=1, Tests=3,  1 wallclock secs ( 0.03 usr  0.01 sys +  1.05 cusr  0.05 csys =  1.14 CPU)
Result: PASS

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>