Bug 14598: [QA Follow-up] Small changes

Bug 14598: [QA Follow-up] Small changes

[1] Renames the dbrev version to XXX; adding a my for $sth, although
    not strictly necessary it feels better.
[2] Circulation.t stumbles over:
    Undefined subroutine &C4::Circulation::GetItem called at ... line 1283.
    Somehow this is related to use_ok instead of a regular use.
    Worked around this by require_ok and adding a regular use.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 3660c451a36db128c143b6388d0d1f34babff4ac)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>