Optimize java util logging configuration

[aslo]

https://github.com/GoogleCloudPlatform/jetty-runtime/pull/185 changed the way we recommend configuring java util logging properties files s.t. we now recommend using JETTY_ARGS instead of JAVA_USER_OPTS. This change introduced the possibility of conflicts between the java system properties generated by start.jar and the properties passed in after start.jar is run.

We should investigate to see if there's a better way to manage this configuration.