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>

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

@@ -95,14 +95,14 @@ services:
       LOGFLAG: ${LOGFLAG}
     restart: unless-stopped
   retriever-neo4j-llamaindex:
-    image: ${REGISTRY:-opea}/retriever-neo4j-llamaindex:${TAG:-latest}
+    image: ${REGISTRY:-opea}/retriever:${TAG:-latest}
     container_name: retriever-neo4j-server
     depends_on:
       - neo4j-apoc
       - tgi-gaudi-service
       - tei-embedding-service
     ports:
-      - "6009:6009"
+      - "7000:7000"
     ipc: host
     environment:
       no_proxy: ${no_proxy}
@@ -111,7 +111,7 @@ services:
       host_ip: ${host_ip}
       HUGGING_FACE_HUB_TOKEN: ${HUGGINGFACEHUB_API_TOKEN}
       HF_TOKEN: ${HF_TOKEN}
-      NEO4J_URL: ${NEO4J_URL}
+      NEO4J_URI: ${NEO4J_URL}
       NEO4J_USERNAME: ${NEO4J_USERNAME}
       NEO4J_PASSWORD: ${NEO4J_PASSWORD}
       TGI_LLM_ENDPOINT: ${TGI_LLM_ENDPOINT}
@@ -122,6 +122,7 @@ services:
       EMBEDDING_MODEL_ID: ${EMBEDDING_MODEL_ID}
       LLM_MODEL_ID: ${LLM_MODEL_ID}
       LOGFLAG: ${LOGFLAG}
+      RETRIEVER_COMPONENT_NAME: "OPEA_RETRIEVER_NEO4J"
     restart: unless-stopped
   graphrag-gaudi-backend-server:
     image: ${REGISTRY:-opea}/graphrag:${TAG:-latest}
@@ -139,7 +140,7 @@ services:
       - http_proxy=${http_proxy}
       - MEGA_SERVICE_HOST_IP=graphrag-gaudi-backend-server
       - RETRIEVER_SERVICE_HOST_IP=retriever-neo4j-llamaindex
-      - RETRIEVER_SERVICE_PORT=6009
+      - RETRIEVER_SERVICE_PORT=7000
       - LLM_SERVER_HOST_IP=tgi-gaudi-service
       - LLM_SERVER_PORT=${LLM_SERVER_PORT:-80}
       - LOGFLAG=${LOGFLAG}