OPENDJ-2468 Fix authrate tool

The tool was broken since d750ad39895.
Problem was that we tried to rebind with the bind request template in
the PerformanceRunner (see changes done in PerformanceRunner in
d750ad39895).
We do not want to rebind in authrate tool.
To fix that, a field bindRequestTemplate has been added to the
AuthRate.BindPerformanceRunner.
This prevent us to use the bindRequest needed by the other tool to
perform rebinds.