Bug 15504: (QA follow-up) Final changes

Bug 15504: (QA follow-up) Final changes

[1] Comment in Patron->is_active sharpened.
[2] Patron->update_lastseen
      return if $cached && $cached eq $now->ymd;
    Should be
      return $self if $cached && $cached eq $now->ymd;
    Consistent return value.
[3] Typo if there are not TrackLastPatronActivityTriggers enabled
[4] Typo TrackLastPatronActivityTriggers must be contain
[5] Typo patron is does .. option => performs an action
[6] Tidy on dbrev to fix
      The file is less tidy than before (bad/messy lines before: 0, now: 4)

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>