detect/alert: make sure that signatures with `drop` action are respected, even if the alert is discarded
Considering that an alert could be discarded from the packet queue due to queue size limitations, we must consider how signatures with the `drop` action are still taken into account, even if the respective alert is dropped.
I guess... thought must also be given with regards to how do we indicate what is going on with said traffic, even if the alert isn't kept. Debug log? Specific stats counter?