[Improve][CDC][MySQL] Ennable binlog watermark compare (#4293)

Author: hailin0

seatunnel-connectors-v2/connector-cdc/connector-cdc-mysql/src/main/java/org/apache/seatunnel/connectors/seatunnel/cdc/mysql/source/reader/fetch/scan/MySqlSnapshotFetchTask.java

@@ -75,13 +75,8 @@ public void execute(FetchTask.Context context) throws Exception {
 
         // optimization that skip the binlog read when the low watermark equals high
         // watermark
-
-        // TODO make binlogBackfillRequired configable.
-        // TODO we need store the data in disk to ensure no memory overflow
-        // final boolean binlogBackfillRequired =
-        //
-        // backfillBinlogSplit.getStopOffset().isAfter(backfillBinlogSplit.getStartupOffset());
-        final boolean binlogBackfillRequired = false;
+        final boolean binlogBackfillRequired =
+                backfillBinlogSplit.getStopOffset().isAfter(backfillBinlogSplit.getStartupOffset());
         if (!binlogBackfillRequired) {
             dispatchBinlogEndEvent(
                     backfillBinlogSplit,