Bug 17742: Fix t/db_dependent/Patrons.t

Bug 17742: Fix t/db_dependent/Patrons.t

Moves the getting of testing date for updated_on just after the storing
the test patron data to make the gap between generating data and now
date as short as possible

Fixes test 7

Use Koha::Database instead of C4::Context->dbh

Test plan
1. prove t/db_dependent/Patrons.t
2. read the diff

NOTE: Only minor improvement could be using test builder to
      generate the category and branch codes, rather than assume
      data exists. However, that is beyond scope of this bug.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>