Frequent lucene-stats in logs triggered when closing temporary index (RAMDirectory)

Issue Summary

Log can be flooded with [lucene-stats] entries when using TemporaryIndexProvider Jira service.

Expected Results

Closing an index writer from a RAMDirectory should not trigger printing [lucene-stats] as closing this index is done frequently and is a cheap operation. 

Actual Results

The following log can appear frequently when service: TemporaryIndexProvider is used.

INFO [lucene-stats] flush stats: snapshotCount=4, totalCount=4, periodSec=0, flushIntervalMillis=5, indexDirectory=null, indexWriterId=com.atlassian.jira.index.MonitoringIndexWriter@78f90d8b, indexDirectoryId=RAMDirectory@6f88c034 lockFactory=org.apache.lucene.store.SingleInstanceLockFactory@14369056

Workaround

Add "com.atlassian.jira.index.MonitoringIndexWriter" custom package to logging and profiling in JIRA and set the debug log level to ERROR.
That is until JIRA is restarted. To get the setting permanent, it'll need to be added to log4.properties file as per this article:
https://confluence.atlassian.com/adminjiraserver073/logging-and-profiling-861253813.html
Note that this log should be turned back to default when this issue is fixed.
For any other type of index this log provides valuable statistics allowing to detect performance problems with indexing.