Bug 9394: (follow-up) modernize test cases

Bug 9394: (follow-up) modernize test cases

- wrap in a transaction
- create the patron records needed for the test

To test:

[1] Run prove -v t/db_dependent/Holds.t
[2] Verify that all tests have passed.
[3] Verify that the additional patron records created
    by the test no longer exist in the database.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>