Fix OperationTimer Unit Tests that are Failing

Motivation
----------
There were tests that were failing because the minimum log level for the
OperationTimer had changed from INFO to DEBUG.

Modifications
-------------
In each test the LogLevel was changed from INFO to DEBUG

Result
------
The tests now pass

Change-Id: I53aee9db0adcda2d3bebc75615c3443af1187426
Reviewed-on: http://review.couchbase.org/44442
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Simon Baslé <simon@couchbase.com>