Use default sensor qos for sensor topics

[ruffsl]

Sensor data
For sensor data, in most cases it’s more important to receive readings in a timely fashion, rather than ensuring that all of them arrive. That is, developers want the latest samples as soon as they are captured, at the expense of maybe losing some. For that reason the sensor data profile uses best effort reliability and a smaller queue depth.
https://index.ros.org/doc/ros2/Concepts/About-Quality-of-Service-Settings/#qos-profiles

References:

• https://design.ros2.org/articles/qos.html
• https://github.com/ros2/rmw/blob/release-latest/rmw/include/rmw/qos_profiles.h

[ruffsl]

This could effect the rosbag recording, given rosbag does not of yet auto discover QoS setting:
ros2/rosbag2#125

[emersonknapp]

Rosbag2 can now correctly record SensorData QoS profiles as of ros2/rosbag2#355 - this change will be in the Foxy release