Removing misleading error message

This function (_get_instances_on_driver) was reporting instances are on the
hypervisor and not in the database with no consideration for the filters being
used in the database query. This resulted in error log messages indicating running
instances were not in the database when in fact the query was filtering for deleted
instances.

To avoid misleading error logs of this nature I've removed the logging from the
function. Currently the locations which call this function provide more accurate
logging on the state of the instances that are returned based on the filters they
have called _get_instances_on_driver with.

bug 1183276

Change-Id: I4ee52fe417f73a90cf157bc531b483be93e34275
Merge "Removing misleading error message"