Chore/remove extra docker middleware variables (#5836)

Co-authored-by: dahuahua <38651850@qq.com>

docker/middleware.env.example

@@ -10,12 +10,6 @@ POSTGRES_DB=dify
 PGDATA=/var/lib/postgresql/data/pgdata
 
 
-# ------------------------------
-# Environment Variables for qdrant Service
-# (only used when VECTOR_STORE is qdrant)
-# ------------------------------
-QDRANT_API_KEY=difyai123456
-
 # ------------------------------
 # Environment Variables for sandbox Service
 SANDBOX_API_KEY=dify-sandbox
@@ -37,7 +31,6 @@ SSRF_SANDBOX_HOST=sandbox
 
 # ------------------------------
 # Environment Variables for weaviate Service
-# (only used when VECTOR_STORE is weaviate)
 # ------------------------------
 WEAVIATE_QUERY_DEFAULTS_LIMIT=25
 WEAVIATE_AUTHENTICATION_ANONYMOUS_ACCESS_ENABLED=true