Reflectometry: Server causes flickering "moving" status

As a reflectometry scientist I would like the "In motion" status of IBEX to be reflected accurately. At the moment, the server sets `CS:MOT:MOVING` to true while it is processing which was added as part of https://github.com/ISISComputingGroup/IBEX/issues/5744, however this causes the status to flicker even if the value has not actually changed. We should prevent this from happening as it causes confusion.

#### Acceptance Criteria
- The reflectometry server does not set the server status to in motion unless something is actually moving
- Retain current behaviour of the "moving" status not being cleared before beamline parameters have reached their final RBV