Timing out thread pool workers should log at VLOG(3)
Timing out thread pool workers should log at VLOG(3)

This type of thing will happen all the time during typical usage, it's
noisy and kind of scary looking. Also clarify the log message.

Change-Id: Ic418dc42841f1bab532299f543f85581c8fb472f
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3553
Tested-by: jenkins
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>

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