fix(core): make value in yaml compatible with strict parser (#1037)

Because

seems in image build environment using strict(or old) yaml parser for
docker compose.

This commit

use string instead of bool

docker-compose.yml

@@ -569,7 +569,7 @@ services:
     image: ${MILVUS_IMAGE}:${MILVUS_VERSION}
     restart: unless-stopped
     environment:
-      ETCD_USE_EMBED: true
+      ETCD_USE_EMBED: "true"
       COMMON_STORAGETYPE: local
     command: milvus run standalone 1> /dev/null
     healthcheck: