Get schedules to end closer to when they're told to

[kmharrington]

Right now it looks like schedules end at the last telescope scan, but that can leave the telescope in non sun-safe states.

Ex: I have t1 (end time) set to be 17:00 UTC which is in the middle of the sun break. When I do this, the last lines in the schedule are

run.smurf.bias_step(concurrent=True)
run.seq.scan(
    description='NW',
    stop_time='2024-11-24T14:13:00+00:00',
    width=40.0, az_drift=0,
    subtype='cmb', tag='271-311',
    min_duration=600,
)

This should be the last scan before the sun stow period, but that scan ends nearly 3hrs before I was expecting this schedule to end. We also know from sun safety rules that the telescope cannot be left in that position for three hours. So we need to handle the end of the schedules differently.