app-layer-expectation: clean expectation at flow end

app-layer-expectation: clean expectation at flow end

When a flow timeout, we can have still existing expectations that
are linked to this flow. Given that there is a delay between the
real ending of the flow and its destruction by Suricata, the
expectation should be already honored so we can assume the risk
to clean the expectations that have been triggered by the
to-be-deleted flow.