fix

e2e_test/streaming/rate_limit/upstream_amplification.slt

@@ -18,6 +18,9 @@ WITH (
     datagen.rows.per.second = '10000'
 ) FORMAT PLAIN ENCODE JSON;
 
+statement ok
+SET BACKGROUND_DDL=true;
+
 statement ok
 CREATE SINK sink AS
     SELECT x.i1 as i1 FROM source_table x
@@ -26,6 +29,9 @@ CREATE SINK sink AS
                 JOIN source_table s3 ON x.i1 = s3.i1
     WITH (connector = 'blackhole');
 
+statement ok
+SET BACKGROUND_DDL=false;
+
 # The following sequence of FLUSH should be fast, since barrier should be able to bypass sink.
 # Otherwise, these FLUSH will take a long time to complete, and trigger timeout.
 statement ok