Stale acu position data in hwp supervisor during check_acu_ok_for_spinup()

[BrianJKoopman]

Related to this issue, satp3 had similar problem on Nov 29th 2024, by following schedule https://site.simonsobs.org/satp3/nextline/db/runs/2202

run.wait_until('2024-11-29T18:44:23.980000+00:00')
run.acu.move_to(az=180.0, el=40.0)
run.acu.move_to(az=180.0, el=48.0)
######## HWP spinning up ##########
run.hwp.set_freq(freq=2) # start HWP rotation

In this case, I think the safety was triggered due to the time lag of acu monitoring.
hwp spin up was called right after the telescope has moved from 40 to 48, and the hwp_supervisor checked the acu position that was updated slightly before, and it was lower than 48.
One of the solutions is to just add a time buffer in the schedule.

Originally posted by @ykyohei in #788 (comment)

As discussed in that original thread, it seems most likely the HWP supervisor has an outdated cache of the ACU elevation. Can we force a hwp_state.acu.update() at the start of check_acu_ok_for_spinup()?

[jlashner]

Yes, I think forcing a state update before a check like this is reasonable. I can implement that.