[hotfix][oceanbase] Reduce OceanBase container memory requirements for CI

Set OB_MEMORY_LIMIT=2G and OB_SYSTEM_MEMORY=512M to fit within
GitHub Actions runner's ~7GB memory. The default OB_MEMORY_LIMIT
is 6G which causes OBD-5000 "not enough memory" error when the
runner is already occupied by other connector test containers.

Also reduce OB_LOG_DISK_SIZE from 4G to 2G and increase startup
timeout from 4 to 6 minutes for better reliability.

Author: yuanoOo

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-oceanbase-cdc/src/test/java/org/apache/flink/cdc/connectors/oceanbase/OceanBaseTestUtils.java

@@ -38,15 +38,17 @@ public class OceanBaseTestUtils {
 
     public static OceanBaseContainer createOceanBaseContainerForJdbc() {
         return createOceanBaseContainer(OB_4_3_3_VERSION, "mini")
-                .withStartupTimeout(Duration.ofMinutes(4));
+                .withStartupTimeout(Duration.ofMinutes(6));
     }
 
     public static OceanBaseContainer createOceanBaseContainer(String version, String mode) {
         return new OceanBaseContainer(version)
                 .withMode(mode)
                 .withTenantPassword(TEST_PASSWORD)
+                .withEnv("OB_MEMORY_LIMIT", "2G")
+                .withEnv("OB_SYSTEM_MEMORY", "512M")
                 .withEnv("OB_DATAFILE_SIZE", "2G")
-                .withEnv("OB_LOG_DISK_SIZE", "4G")
+                .withEnv("OB_LOG_DISK_SIZE", "2G")
                 .withLogConsumer(new Slf4jLogConsumer(LOG));
     }
 }