Use xray centring params for grid detection

[DominicOram]

Currently the code in #584 uses loopCentring parameters rather than xrayCentring this is because it relies on max_tip_distance being in the file, which it uses to disregard oddly shaped pins. The code in GDA does not disregard oddly shaped pins for xray centring and so doesn't need this parameter.

Acceptance Criteria

• Artemis uses the xrayCentring parameters