fix(api): move axes separately in movetomaint

I don't know why this would stop working now, but something we did makes
the right mount move faster than the left mount when we're moving to the
maintenance position to detach the 96 mount plate, so it trips over its
own feet.

api/src/opentrons/protocol_engine/commands/calibration/move_to_maintenance_position.py

@@ -108,10 +108,15 @@ async def execute(
                 await ot3_api.move_axes(
                     {
                         Axis.Z_L: max_motion_range + _LEFT_MOUNT_Z_MARGIN,
+                    }
+                )
+                await ot3_api.disengage_axes([Axis.Z_L])
+                await ot3_api.move_axes(
+                    {
                         Axis.Z_R: max_motion_range + _RIGHT_MOUNT_Z_MARGIN,
                     }
                 )
-                await ot3_api.disengage_axes([Axis.Z_L, Axis.Z_R])
+                await ot3_api.disengage_axes([Axis.Z_R])
 
         return SuccessData(public=MoveToMaintenancePositionResult(), private=None)