Depend on a proper kernel package

only marking as WIP since deb-build-jobs!168 (merged) needs to go in first.

We trigger this by a build profile so we can disable it in CI where we still want to fetch latest kernels via wget.

We don't make this architecture dependent since that would mean switching librem5-base to arch any which in turn would mean having separate germinate lists for arm64 and amd64. We might want to do that later on when switching to seeds to fill the package lists (which we can do now that we build off of pureos as well).