Omegascans are not delayed long enough for EW alerts

It doesn't seem like all the omegascans can be generated 10 seconds after t_0, since the longest omegascan requires 10 seconds of data before the event. Thus a longer delay is required for the data to be transferred to CIT, etc. I suggest delaying by another further 10 seconds.

eg failure: https://gracedb-playground.ligo.org/superevents/S200319cj/view/, omegascans generated+uploaded 10 seconds from t_0 eg success: https://gracedb-playground.ligo.org/superevents/S200319ai/view/, omegascans generated+uploaded 45 seconds from t_0.