Support single bucket for experiments

[mcopik]

We shouldn't use more than three buckets; for code, experiments, and benchmark data.

• [x] Use a dedicated name for resources, retained in cache across invocations.
• [x] Recover the resource name from existing deployments.
• [x] Support a single bucket for experiments.
• [x] Support a single bucket for all benchmark data.
• [x] Support a single bucket for code (411 on AWS).