Fix MINIO_*_KEY deprecation warning and make server config more customizable

[ghost]

about 4 months ago minio introduced a change that deprecated the variables MINIO_ACCESS_KEY and MINIO_SECRET_KEY and replaced them with MINIO_ROOT_USER and MINIO_ROOT_PASSWORD respectively. internally they are handled the same

this non-breaking change works well, because ansible users can just replace their variables and it still works without having to restart or redeploy the whole infra stack. (most likely)

during deployment we found that being able to set the minio_server_addr wasn't detailed enough, it's nice to split it into port + ip/fqdn