Bug 17234: Two new functions lack tests

Bug 17234: Two new functions lack tests

This adds two tests to t/db_dependent/Installer.t

TEST PLAN
---------
1) Apply patch
2) prove -v t/db_dependent/Installer.t
   -- column and constraint tests were added.
3) run koha qa test tools

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 8938631f38bb22456424219d3c3453493df6f848)
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
(cherry picked from commit 4518ec795d253901215621235f3c1bf6e76f4df0)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>