ZTF alerts can arrive late

[JulienPeloton]

Describe the issue

Our scheduler stops Fink at 5pm Paris time (raw2science & distribute) and 7pm Paris time (stream2raw). While this is OK for a "normal" night in California (8am & 10am respectively), this is not enough if there are delays in the alert distribution... todo: stops Fink real-time pipeline just before database operations at 8pm Paris time.