[SPARK-35226][SQL][FOLLOWUP] Fix test added in SPARK-35226 for DB2Krb…

…IntegrationSuite

### What changes were proposed in this pull request?

This PR fixes an test added in SPARK-35226 (#32344).

### Why are the changes needed?

`SELECT 1` seems non-valid query for DB2.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

DB2KrbIntegrationSuite passes on my laptop.

I also confirmed all the KrbIntegrationSuites pass with the following command.
```
build/sbt -Phive -Phive-thriftserver -Pdocker-integration-tests "testOnly org.apache.spark.sql.jdbc.*KrbIntegrationSuite"
```

Closes #32632 from sarutak/followup-SPARK-35226.

Authored-by: Kousuke Saruta <sarutak@oss.nttdata.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/DockerKrbJDBCIntegrationSuite.scala

@@ -178,19 +178,7 @@ abstract class DockerKrbJDBCIntegrationSuite extends DockerJDBCIntegrationSuite
             .option("keytab", keytabFullPath)
             .option("principal", principal)
             .option("refreshKrb5Config", "true")
-            .option("query", "SELECT 1")
-            .load()
-        }
-
-        // Set the authentic krb5.conf but doesn't refresh config
-        // so this assertion is expected to fail.
-        intercept[Exception] {
-          sys.props(KRB5_CONF_PROP) = origKrb5Conf
-          spark.read.format("jdbc")
-            .option("url", jdbcUrl)
-            .option("keytab", keytabFullPath)
-            .option("principal", principal)
-            .option("query", "SELECT 1")
+            .option("dbtable", "bar")
             .load()
         }
 
@@ -200,11 +188,11 @@ abstract class DockerKrbJDBCIntegrationSuite extends DockerJDBCIntegrationSuite
           .option("keytab", keytabFullPath)
           .option("principal", principal)
           .option("refreshKrb5Config", "true")
-          .option("query", "SELECT 1")
+          .option("dbtable", "bar")
           .load()
-        val result = df.collect().map(_.getInt(0))
+        val result = df.collect().map(_.getString(0))
         assert(result.length === 1)
-        assert(result(0) === 1)
+        assert(result(0) === "hello")
       } finally {
         sys.props(KRB5_CONF_PROP) = origKrb5Conf
       }