Add new testnet preset

[norswap]

Right now we have a dev and prod preset. But in reality, our prod preset is really a tesnet preset, in particular the deploy config is largely copied from the OP monorepo Goerli deploy config (the most striking example is the finalization period is 12s instead of one week). This should become a "testnet" (or test for short) preset, while we should copy the mainnet config for the prod config.