Description
There are a few classes that directly rely on log4j to be on the classpath instead and don't use the slf4j logging facade. This creates problems when trying to switch the logging implementation.
1. org.apache.solr.core.ZkContainer
I don't know the impact of this change, but shouldn't this call `org.apache.solr.logging.MDCLoggingContext.clear()` ?
2. org.apache.solr.handler.component.RangeFacetProcessor and org.apache.solr.handler.component.RangeFacetRequest
should use slf4j instead of log4j
I had a stab at it at