[SPARK-27155][TEST] Parameterize Oracle docker image name

## What changes were proposed in this pull request?

Update Oracle docker image name.

## How was this patch tested?

./build/mvn test -Pdocker-integration-tests -pl :spark-docker-integration-tests_2.12

Closes #24086 from lipzhu/SPARK-27155.

Authored-by: Zhu, Lipeng <lipzhu@ebay.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>

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

@@ -39,13 +39,16 @@ import org.apache.spark.tags.DockerTest
  * while Spark QA test run.
  *
  * The following would be the steps to test this
- * 1. Pull oracle 11g image - docker pull wnameless/oracle-xe-11g
- * 2. Start docker - sudo service docker start
- * 3. Download oracle 11g driver jar and put it in maven local repo:
+ * 1. Build Oracle database in Docker, please refer below link about how to.
+ *    https://github.com/oracle/docker-images/blob/master/OracleDatabase/SingleInstance/README.md
+ * 2. export ORACLE_DOCKER_IMAGE_NAME=$ORACLE_DOCKER_IMAGE_NAME
+ *    Pull oracle $ORACLE_DOCKER_IMAGE_NAME image - docker pull $ORACLE_DOCKER_IMAGE_NAME
+ * 3. Start docker - sudo service docker start
+ * 4. Download oracle 11g driver jar and put it in maven local repo:
  *    (com/oracle/ojdbc6/11.2.0.2.0/ojdbc6-11.2.0.2.0.jar)
- * 4. The timeout and interval parameter to be increased from 60,1 to a high value for oracle test
+ * 5. The timeout and interval parameter to be increased from 60,1 to a high value for oracle test
  *    in DockerJDBCIntegrationSuite.scala (Locally tested with 200,200 and executed successfully).
- * 5. Run spark test - ./build/sbt "test-only org.apache.spark.sql.jdbc.OracleIntegrationSuite"
+ * 6. Run spark test - ./build/sbt "test-only org.apache.spark.sql.jdbc.OracleIntegrationSuite"
  *
  * All tests in this suite are ignored because of the dependency with the oracle jar from maven
  * repository.
@@ -55,7 +58,7 @@ class OracleIntegrationSuite extends DockerJDBCIntegrationSuite with SharedSQLCo
   import testImplicits._
 
   override val db = new DatabaseOnDocker {
-    override val imageName = "wnameless/oracle-xe-11g:16.04"
+    override val imageName = sys.env("ORACLE_DOCKER_IMAGE_NAME")
     override val env = Map(
       "ORACLE_ROOT_PASSWORD" -> "oracle"
     )