Log quota refresh in_use message at INFO level for logstash

Commit 5aef26496786c02a1ed324bbd2eb0b9994a2018d added the log message to
give some idea when we're unnecessarily refreshing quota usage.

Logstash only collects INFO+ level messages, so bump this to an INFO
level message so we can track gate runs to see if this is actually a
problem.

Related-Bug: #1353962

Change-Id: I60ffa9dbda22e252f290bf316fa2e472d3e92f2f
Merge "Log quota refresh in_use message at INFO level for logstash"