[partition] Reduce logging for mounted partitions

- The other log entries say when something is possible,
   not when something is **not** possible.

src/modules/partition/gui/ChoicePage.cpp

@@ -1248,7 +1248,6 @@ ChoicePage::setupActions()
         }
         if ( (*it)->isMounted() )
         {
-            cDebug() << Logger::SubEntry() << "contains mounted (un-eraseable)" << it;
             atLeastOneIsMounted = true;
         }
     }