fix: multiple docker builder searcher support

[iowar]

docker-compose up -d --scale builder=3

[kant777]

yeah thought about this but this is not a real scenario since it uses different folder under same volume. so if log into the container I will access to all keys. It is ok for a play env but I am trying to come up with some thing that is as close as possible to the real scenarios.

[aloknerurkar]

I dont mind this as an interim solution unless @kant777 already has something in mind!. The PR changes LGTM!

[iowar]

remove old containers, volumes and images
docker rm -f $(docker ps -qa)
docker volume rm mev-commit_bootnode-keys mev-commit_builder-keys mev-commit_searcher-keys
docker image rm -f $(docker images|grep "mev-com"|awk -F " " '{print $3}'|head -n1)