Bug 17431: Fix failing test t/db_dependent/api/v1/holds.t

Bug 17431: Fix failing test t/db_dependent/api/v1/holds.t

This patch fixed failing test for t/db_dependent/api/v1/holds.t which was broken
after Bug 14695.

$ perl t/db_dependent/api/v1/holds.t
...
not ok 42 - similar match for JSON Pointer "/error"
    #   Failed test 'similar match for JSON Pointer "/error"'
    #   at t/db_dependent/api/v1/holds.t line 291.
    #                   'Reserve cannot be placed. Reason: itemAlreadyOnHold'
    #     doesn't match '(?^u:tooManyReserves)'
    # Looks like you failed 1 test of 42.
not ok 4 - Test endpoints with permission

To test:
1. Run t/db_dependent/api/v1/holds.t and observe it fail.
2. Apply patch.
3. Run the test again and observe it pass.

Signed-off-by: Marc <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>