config: turn off fan for andor3 only

only for testing, and during testing the fan is not handy
driver andorcam3: clean up
driver andorcam2: reduce time to wait for the new acquisition

Similar to andorcam3, sleeping the entire expected time of the acquisition can be too long
so just keep checking if the acquisition is over.

Also fix the simulator to correctly simulate such behaviour.
driver andorcam*: fix synchronised acquisition with late events

If 2 late events in a row, it could happen that the second events try to start
the acquisition before the current one is over.

also increase SEM dwell time in tests to work with Clara.