Currently there fields called swarming_service_account and service_account in the project config, but the values that are put there aren't actually used for anything.

If we actually want to use these service accounts for making requests to swarming (or other dependencies, e.g. buildbucket or gerrit?) we should use them.

Otherwise, if we're ok with always using the tricium instance service account, then we should remove these fields from the configs.