sinkv2(ticdc): rename

cdc/sinkv2/eventsink/event_appender.go

@@ -69,21 +69,21 @@ func (t *TxnEventAppender) Append(
 			continue
 		}
 
-		currentLastTxn := buffer[len(buffer)-1]
+		lastTxn := buffer[len(buffer)-1]
 		// Normally, this means the commitTs grows.
-		if currentLastTxn.GetCommitTs() != row.CommitTs ||
+		if lastTxn.GetCommitTs() != row.CommitTs ||
 			// Normally, this means we meet a new big txn batch.
 			row.SplitTxn ||
 			// Normally, this means we meet a new txn.
-			currentLastTxn.StartTs < row.StartTs {
+			lastTxn.StartTs < row.StartTs {
 			// Fail-fast check
-			commitTsDecreased := currentLastTxn.GetCommitTs() > row.CommitTs
+			commitTsDecreased := lastTxn.GetCommitTs() > row.CommitTs
 			if commitTsDecreased {
 				log.Panic("The commitTs of the emit row is less than the received row",
 					zap.Uint64("lastReceivedCommitTs", buffer[len(buffer)-1].GetCommitTs()),
 					zap.Any("row", row))
 			}
-			startTsDecreased := currentLastTxn.StartTs > row.StartTs
+			startTsDecreased := lastTxn.StartTs > row.StartTs
 			if startTsDecreased {
 				log.Panic("The startTs of the emit row is less than the received row",
 					zap.Any("lastReceivedStartTs", buffer[len(buffer)-1].GetCommitTs()),