Bug 21547: (follow-up) Rely on Koha::Patron->set_password checks

Bug 21547: (follow-up) Rely on Koha::Patron->set_password checks

This patch makes the controller just call $patron->set_password and use
the exceptions it might raise instead of manually checking the passwor
strength.

No behaviour change should be expected. It also removes some leftovers.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 3f734900f0a86e5478afc22cb77b493500e998e9)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>