Removing groups on triggers, deleting triggers

[LeahBreedenNyaruka]

Currently, you cannot delete a contact group if it's being used on a trigger, even if archived. Archived triggers cannot be deleted and the only way to remove the group is to add a different group or contact since scheduled triggers need to have at least one contact and will not allow you to save the update without that field.

Users need to be able to delete triggers easily and/or remove groups entirely.