Remove `_set_open_seq()` if it is not required

`_set_open_seq()` may not be required if the ioc clears the open pv. The current implementation mimics how the edm screen button uses the pv but it may not be necessary to set it inactive after a delay.

1. Test just writing a 1 to the open pv and check if it is cleared
2. Remove `_set_open_seq()` if it is cleared by the ioc

https://github.com/DiamondLightSource/dodal/blob/6e6d32b69e37ef74b5569a87c092c2335a0c7bf2/src/dodal/devices/pressure_jump_cell.py#L75-L79