Panda: Agamemnon should use smaller exposure if panda is on

When we are running the XRC with the panda turned on we can run at a faster rate, an exposure time of 0.002ms rather than 0.004ms. At the moment, when we get an instruction from Agamemnon we just use the default grid expose time, we should instead use the faster time if the panda is enabled

## Acceptance Criteria
- We use a shorter exposure time on gridscans from agamemnon when the panda is on