Dynamically create the service_conf.yaml file by replacing environment variables from .env (#3341)

### What problem does this PR solve?

This pull request implements the feature mentioned in #3322. 

Instead of manually having to edit the `service_conf.yaml` file when
changes have been made to `.env` and mapping it into the docker
container at runtime, a template file is used and the values replaced by
the environment variables from the `.env` file when the container is
started.
 

### Type of change

- [X] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>
Co-authored-by: Zhichang Yu <yuzhichang@gmail.com>

docker/docker-compose-gpu.yml

@@ -16,7 +16,6 @@ services:
       - 80:80
       - 443:443
     volumes:
-      - ./service_conf.yaml:/ragflow/conf/service_conf.yaml
       - ./ragflow-logs:/ragflow/logs
       - ./nginx/ragflow.conf:/etc/nginx/conf.d/ragflow.conf
       - ./nginx/proxy.conf:/etc/nginx/proxy.conf