The following only resides in core-default.xml and doesn't look like its used anywhere at all. At least a grep of the prop name and parts of it does not give me back anything at all.
These settings are now configurable via generic Log4J opts, via the shipped log4j.properties file in the distributions.
137 <!--- logging properties -->
142 <description>The max size of each log file</description>
148 <description>The max number of log files</description>