test(bigquery): warm up client in beforeClass to stabilize testFastSQLQueryMultiPage

b/467064659

Author: jinseopkim0

java-bigquery/google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/it/ITBigQueryTest.java

@@ -1184,6 +1184,9 @@ static void beforeClass() throws InterruptedException, IOException {
     Job jobLargeTable = bigquery.create(JobInfo.of(configurationLargeTable));
     jobLargeTable = jobLargeTable.waitFor();
     assertNull(jobLargeTable.getStatus().getError());
+
+    // Warmup query to initialize connection and avoid cold start timeout in subsequent tests
+    bigquery.query(QueryJobConfiguration.of("SELECT 1"));
   }
 
   @AfterAll
@@ -4853,7 +4856,7 @@ void testFastSQLQueryMultiPage() throws InterruptedException {
     assertNotNull(result1.getNextPageToken());
     assertTrue(result1.hasNextPage());
 
-    config.toBuilder().setQuery(query).build();
+    config = config.toBuilder().setQuery(query).build();
     TableResult result2 = bigquery.query(config);
     assertNotNull(result2.getJobId());
     assertEquals(LARGE_TABLE_SCHEMA, result2.getSchema());