[FIXED JENKINS-21386] Allow more specific loggers to reduce log level

This change uses the most specific log recorder (based on name) to determine whether a log message should be added.

If both `com` (at `INFO`) and `com.example` (at `WARNING`) are defined for a specific log recorder, a log message in logger `com.example.Foo` will only be logged of it's `WARNING` or `SEVERE`, as `com.example` is more specific than `com`.

Might reduce existing log recorders' effective logging output if they have a currently useless configuration of specific loggers having a more relaxed log level than a less specific logger.

This PR is one of two proposed solutions to [JENKINS-21386](https://issues.jenkins-ci.org/browse/JENKINS-21386), the other being #1091.