Bug 16607: Remove CPL/MPL from two unit tests

Bug 16607: Remove CPL/MPL from two unit tests

Test t/db_dependent/Accounts.t:
This test created a MPL branch, but did not use it any more.

Test t/db_dependent/Items/AutomaticItemModificationByAge.t:
This test still used CPL/MPL branches. Now it uses two new branches.

Test plan:
[1] Run t/db_dependent/Accounts.t.
[2] Run t/db_dependent/Items/AutomaticItemModificationByAge.t.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Both tests pass OK
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>