Bug 21610: (QA follow-up) Better use columns_info from DBIx

Bug 21610: (QA follow-up) Better use columns_info from DBIx

We should better use the published method than a private hash key.
And shorter to go via _result than adding a new schema call.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 8625eefc76a9390e28e9136f19b9767814bc27a5)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>