Add an option to disable creating log files by the launch system

Feature request

Add an option to disable creating log files by the launch system.

Feature description

We deploy a ROS application which uses the launch subsystem using docker containers. We try to follow well known industry guidelines like Heroku's 12-factor app https://12factor.net/logs. This guideline states that the application should not force creating log files but instead it should output log entries using standard streams. This makes a lot of sense, especially if you deploy the application to an embedded device with a flash storage that wears quickly with unnecessary writes.

At the moment is seems that there is no way to disable creating launch.log file as it is created unconditionally in the get_logger function of the launch system: https://github.com/ros2/launch/blob/d9ffd805e3d9ca42fe4dd0019ae095e9eb0d4d72/launch/launch/logging/__init__.py#L350.

Implementation considerations

Start in launch/launch/logging/init.py at get_logger, where launch.log is created unconditionally. Trace how launch options reach this entry point and review the 12-factor requirement for standard-stream output. Done means an option prevents launch.log creation while preserving standard-stream logging, with regression coverage.