Previously we only stored the drvmap, but we will also need the build
chunks to refactor the generation of dynamic post-steps.
Change-Id: I256fffe13af8f8c4521835257f5d87dda323b248
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5043
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: ezemtsov <eugene.zemtsov@gmail.com>