Bug 23994: Fix random failure from AdditionalFields.t (U18)

Bug 23994: Fix random failure from AdditionalFields.t (U18)

t/db_dependent/Koha/Objects/Mixin/AdditionalFields.t .. 1/12
 #   Failed test '->additional_field_values should return the correct values'
 #   at t/db_dependent/Koha/Objects/Mixin/AdditionalFields.t line 82.
 #     Structures begin differing at:
 #          $got->[0]{value} = 'bar value for basket2'
 #     $expected->[0]{value} = 'foo value for basket2'
 # Looks like you failed 1 test of 12.

We do not really know why, but the values are not returned in the order they
are stored in DB. Fixing this random failure for now at test level.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>