ci: enforce stricter condition on ssl_cert_gen dependency

.ci/docker-compose-file/docker-compose-kafka.yaml

@@ -39,9 +39,12 @@ services:
     container_name: kafka-1.emqx.net
     hostname: kafka-1.emqx.net
     depends_on:
-      - "kdc"
-      - "zookeeper"
-      - "ssl_cert_gen"
+      kdc:
+        condition: service_started
+      zookeeper:
+        condition: service_started
+      ssl_cert_gen:
+        condition: service_completed_successfully
     environment:
       KAFKA_BROKER_ID: 1
       KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181