tests/bootkube: move self-host smoke back into main namespace
tests/bootkube: move self-host smoke back into main namespace

Also move self-hosted scale test to enabled in the experimental
namespace.

dm0-/mantle,quantum/coreos-mantle,marineam/mantle,glevand/coreos--mantle,marineam/mantle,quantum/coreos-mantle,dm0-/mantle,glevand/coreos--mantle