fix typo

preprocessor/Dockerfile

@@ -66,6 +66,7 @@ ENV INSTANCE_ID="prism-data-access-server_preprocessor" \
     OS_USER_DOMAIN_NAME_DOWNLOAD= \
     REDIS_HOST="redis" \
     REDIS_PORT="6379" \
+    REDIS_REGISTER_QUEUE_KEY="register_queue" \
     REDIS_PREPROCESS_QUEUE_KEY="preprocess_queue" \
     REDIS_PREPROCESS_MD_QUEUE_KEY="preprocess-md_queue" \
     REDIS_PREPROCESS_FAILURE_KEY="preprocess-failure_set" \