[perf2bolt] Fix print report for pre-aggregated profile

Summary:
For pre-aggregated profile, we were using the number of records in the
profile for `NumTraces` ignoring the counts per record. As a result,
the reported percentage of mismatched traces was bogus.

(cherry picked from FBD15093123)

bolt/src/DataAggregator.cpp

@@ -1407,7 +1407,7 @@ void DataAggregator::processPreAggregated() {
                      AggrEntry.From.Offset, false};
       LBREntry Second{AggrEntry.To.Offset, AggrEntry.To.Offset, false};
       doTrace(First, Second, AggrEntry.Count);
-      ++NumTraces;
+      NumTraces += AggrEntry.Count;
       break;
     }
     }