Bug 24016: Add a failing test for overwrite-able manager_id in Koha::Patron::Message

Bug 24016: Add a failing test for overwrite-able manager_id in Koha::Patron::Message

To test:
1. prove t/db_dependent/Koha/Patron/Messages.t
2. Observe failure

t/db_dependent/Koha/Patron/Messages.t .. 2/12
   Failed test 'Manager id should be overwrite-able even if defined in userenv'
   at t/db_dependent/Koha/Patron/Messages.t line 90.
          got: '1100'
     expected: '1101'
 Looks like you failed 1 test of 12.
t/db_dependent/Koha/Patron/Messages.t .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/12 subtests

Sponsored-by: Koha-Suomi Oy
Signed-off-by: Maryse Simard <maryse.simard@inlibro.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>