LArNoisyROAlg: Use unique Tool names

The names of tools in a PrivateToolHandleArray needs to be unique. This was not the case for the supplemental tools monitoring noise-bursts vs HV-lines that where added a few month ago. The consequence are lengthy WARNING-messages like Py:GaudiHandles WARNING GenericMonitoringTool('EMB_EMBC'..) with instance name 'EMB_EMBC' already in PrivateToolHandleArray. Not adding GenericMonitoringTool('EMB_EMBC'...) and the histogram creating is not actually added to the job.

This MR fixes the problem by pre-pending 'HV' to tool name.

cc @pavol