Update Dockerfiles to use multi-stage build

[loothero]

Currently our katana file:

1. Checkouts Loot Survivor
2. Builds Loot Survivor
3. Deploys Loot Survivor to Katana

We should change this to use multi-stage build process so that we generate the build artifacts during the first stage and then move them into a fresh container alongside katana. This way we don't have the extra bloat of source code in the container running katana+LS

We should do the same with DNA stream as well and anything else that is similar.