message: action: don't prescribe a default takeoff altitude
  Instead of setting a default takeoff altitude just rely on the fact that
  the drone itself has a takeoff altitude set by a parameter. This should
  avoid surprises where taking off with the SDK has a different altitude
  than with other ground stations.
diff: @@ -124,7 +124,6 @@ ActionResult ActionImpl::takeoff() const
  MAVLinkCommands::CommandLong command{};
  command.command = MAV_CMD_NAV_TAKEOFF;
  - command.params.param7 = _relative_takeoff_altitude_m;
  command.target_component_id = _parent->get_autopilot_id();
  return action_result_from_command_result(_parent->send_command(command));
  @@ -321,7 +320,6 @@ void ActionImpl::takeoff_async_continued(MAVLinkCommands::Result previous_result
  MAVLinkCommands::CommandLong command{};
  command.command = MAV_CMD_NAV_TAKEOFF;
  - command.params.param7 = _relative_takeoff_altitude_m;
  command.target_component_id = _parent->get_autopilot_id();
  _parent->send_command_async(command,
  