fix(spells): correct interpretation of end_sec field [NET-346]

[kmd-fl]

To be with correspondence with the docs:

Will not trigger after that timestamp

[linear]

NET-346 Fix spell-event-bus use of `end_sec` field to abrupt spell execution correctly

Right now we are checking that end_sec < now, but we should check end_sec < now + period , so that the spell won't be executed after end_sec at all.