Polish "Add service connection support for Hazelcast"

See gh-42416

spring-boot-project/spring-boot-tools/spring-boot-test-support-docker/src/main/java/org/springframework/boot/testsupport/container/HazelcastContainer.java

@@ -33,4 +33,13 @@ public final class HazelcastContainer extends GenericContainer<HazelcastContaine
 		addExposedPorts(DEFAULT_PORT);
 	}
 
+	/**
+	 * Sets the cluster name.
+	 * @param clusterName the cluster name
+	 * @return this instance
+	 */
+	public HazelcastContainer withClusterName(String clusterName) {
+		return withEnv("HZ_CLUSTERNAME", clusterName);
+	}
+
 }