Update Schema Registry hostname

Author: k-raina

tests/docker/docker-compose.ducktape.yml

@@ -1,4 +1,3 @@
-version: '3'
 services:
   kafka:
     image: confluentinc/cp-kafka:latest
@@ -29,7 +28,7 @@ services:
       - "8081:8081"
     environment:
       SCHEMA_REGISTRY_HOST_NAME: schema-registry
-      SCHEMA_REGISTRY_KAFKASTORE_BOOTSTRAP_SERVERS: kafka:9092
+      SCHEMA_REGISTRY_KAFKASTORE_BOOTSTRAP_SERVERS: localhost:9092
       SCHEMA_REGISTRY_LISTENERS: http://0.0.0.0:8081
       SCHEMA_REGISTRY_KAFKASTORE_TOPIC_REPLICATION_FACTOR: 1
       SCHEMA_REGISTRY_DEBUG: 'true'