LArMonitoring: Don't make duplicate histograms.

LArRODMonAlg and LArRODMonTool try to configure the same histograms.
If we run them in the same job, this can lead to THistSvc crashing
with a double-delete in finalize.  Fix to avoid configuring
LArRODMonTool if the algorithm is requested.

Fixes crash with q220 with --thread=1.