Mercury iPS with fewer than three axes

The Oxford Mercury iPS driver currently assumes a three-axis vector magnet:
https://github.com/microsoft/Qcodes/blob/1280f4a1730a0f70659aec835ce3935a1894de05/src/qcodes/instrument_drivers/oxford/MercuryiPS_VISA.py#L330-L334

For systems with fewer axes than this, the instrument-level parameters like z_ramp do not work / run indefinitely because _ramp_safely() (same for _ramp_simultaneously_blocking()) waits for each axis to return from state "TO SET", which axes that do not exist never do.
https://github.com/microsoft/Qcodes/blob/1280f4a1730a0f70659aec835ce3935a1894de05/src/qcodes/instrument_drivers/oxford/MercuryiPS_VISA.py#L539-L547

The old driver (removed in https://github.com/microsoft/Qcodes/pull/4936/) allowed users to either specify which axes are present or queried the device itself for this information. I'm not sure how readily the current driver admits this due to the use of FieldVector. Can its components of axes that do not exist simply be set to zero always?

Start in src/qcodes/instrument_drivers/oxford/MercuryiPS_VISA.py at the FieldVector setup and the _ramp_safely() and _ramp_simultaneously_blocking() methods referenced in the issue. Compare the current behavior with the old driver removed in PR #4936, including how present axes were specified or queried. Done means instrument-level ramp parameters work for Mercury iPS systems with fewer than three axes without waiting on nonexistent axes.