With the more fine-grained build package set, different images will use
different build pipelines and each of them will be smaller.
We don't currently cache build pipelines so there is no downside to this. Even
when we start caching the difference between having one build pipeline per
image and one shared one is minimal at scale. This will still benefit users
doing one-off builds on-prem.
Most importantly, this tracks things correctly, making pipelines more
composable without having to maintain a global list of dependencies.
No longer name the packageSetChains after the package set, but
keep them named after the pipelines. This should be a
non-functional change as dnf-json does not care about what the
chains are called, only that the names are unique.
