lightning: fix unstable test for conflict detection (pingcap#53225)

ref pingcap#52306

lightning/tests/lightning_duplicate_resolution_merge/run.sh

@@ -24,7 +24,7 @@ LOG_FILE1="$TEST_DIR/lightning_duplicate_resolution_merge1.log"
 LOG_FILE2="$TEST_DIR/lightning_duplicate_resolution_merge2.log"
 
 # let lightning run a bit slow to avoid some table in the first lightning finish too fast.
-export GO_FAILPOINTS="github.com/pingcap/tidb/lightning/pkg/importer/SlowDownImport=sleep(250)"
+export GO_FAILPOINTS="github.com/pingcap/tidb/lightning/pkg/importer/SlowDownImport=sleep(1000)"
 
 run_lightning --backend local --sorted-kv-dir "$TEST_DIR/lightning_duplicate_resolution_merge.sorted1" \
   -d "$CUR/data1" --log-file "$LOG_FILE1" --config "$CUR/config.toml" &