Refactor Retrievers related Examples (#1387)

Delete redundant retrievers docker image in docker_images_list.md.
Refactor Retrievers related Examples READMEs.
Change all of the comps/retrievers/xxx/xxx/Dockerfile path into comps/retrievers/src/Dockerfile.

Fix the Examples CI issues of PR opea-project/GenAIComps#1138.
Signed-off-by: letonghan <letong.han@intel.com>

DocIndexRetriever/docker_compose/intel/hpu/gaudi/README.md

@@ -15,7 +15,7 @@ DocRetriever are the most widely adopted use case for leveraging the different m
 - Retriever Vector store Image
 
   ```bash
-  docker build -t opea/retriever-redis:latest --build-arg https_proxy=$https_proxy --build-arg http_proxy=$http_proxy -f comps/retrievers/redis/langchain/Dockerfile .
+  docker build -t opea/retriever:latest --build-arg https_proxy=$https_proxy --build-arg http_proxy=$http_proxy -f comps/retrievers/src/Dockerfile .
   ```
 
 - Rerank TEI Image

DocIndexRetriever/docker_compose/intel/hpu/gaudi/compose.yaml

@@ -72,7 +72,7 @@ services:
       LOGFLAG: ${LOGFLAG}
     restart: unless-stopped
   retriever:
-    image: ${REGISTRY:-opea}/retriever-redis:${TAG:-latest}
+    image: ${REGISTRY:-opea}/retriever:${TAG:-latest}
     container_name: retriever-redis-server
     depends_on:
       - redis-vector-db
@@ -86,6 +86,7 @@ services:
       REDIS_URL: ${REDIS_URL}
       INDEX_NAME: ${INDEX_NAME}
       LOGFLAG: ${LOGFLAG}
+      RETRIEVER_COMPONENT_NAME: "OPEA_RETRIEVER_REDIS"
     restart: unless-stopped
   tei-reranking-service:
     image: ghcr.io/huggingface/text-embeddings-inference:cpu-1.5