Bug 26043: Fix random failure from Holds.t

Bug 26043: Fix random failure from Holds.t

 #   Failed test 'Test ModReserveMinusPriority()'
 #   at t/db_dependent/Holds.t line 202.
 #          got: undef
 #     expected: '1605'
 # Looks like you failed 1 test of 66.

It is coming from Koha::Patron->holds that is ordering by reservedate,
so "sometimes" they are ordered in reverse (at least it's my
understanding of the problem).

Test plan:
Run the test file several times (from 20 to 60x), it must never fail
with this patch

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 80a611797bf67b263b6b84a6e931833ea336b6a5)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit c98a283d118bb936dc44db1b73cfeb8e45f89a22)

Signed-off-by: Aleisha Amohia <aleishaamohia@hotmail.com>
(cherry picked from commit c106d5a29d32572276489b5b1f3b8941ab17c778)
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>