fix (test)(oracle-xe): update test to verify current user instead of DBA grant

The test now checks the connected session's user rather than verifying DBA grant status, which provides a more direct validation of the system user connection.

Author: cetindogu

modules/oracle-xe/src/test/java/org/testcontainers/junit/oracle/SimpleOracleTest.java

@@ -38,9 +38,11 @@ private void runTestSystemUser(OracleContainer container, String databaseName, S
         assertThat(container.getPassword()).isEqualTo(password);
 
         container.start();
-        ResultSet resultSet = performQuery(container, "GRANT DBA TO " + username);
-        int resultSetInt = resultSet.getInt(1);
-        assertThat(resultSetInt).as("A basic system user query succeeds").isEqualTo(1);
+        ResultSet resultSet = performQuery(container, "SELECT USER FROM DUAL");
+        String currentUser = resultSet.getString(1);
+        assertThat(currentUser)
+            .as("Connected session should run as the system user")
+            .isEqualToIgnoringCase(username);
     }
 
     @Test