Delete wrong multiple takeoffs/landings

[Xenotech81]

Double-check that the SQL committed in 89354cd does not delete wrongly too many flights.
As it is right now, it will delete any landing/takeoff in the past with the same callsign (=flight_id), also days, months, years in the past.
An option would be to consider only flights within a day. But the same flight could land/takeoff several times per day (SAMU44?). Only a time-range filter (of a few minutes?) would be correct.