HPCC-24036 Fix mergeStats mapping in disk write

Signed-off-by: Jake Smith <jake.smith@lexisnexisrisk.com>

thorlcr/activities/thdiskbaseslave.cpp

@@ -437,7 +437,7 @@ void CDiskWriteSlaveActivityBase::close()
             // ensure it is released/destroyed after releasing crit, since the IFileIO might involve a final copy and take considerable time.
             tmpFileIO.setown(outputIO.getClear());
         }
-        mergeStats(stats, tmpFileIO, diskReadRemoteStatistics);
+        mergeStats(stats, tmpFileIO, diskWriteRemoteStatistics);
 
         if (!rfsQueryParallel && dlfn.isExternal() && !lastNode())
         {