`f.ToRawKubeConfigLoader().Namespace()` throws `ErrEmptyConfig` when
default configuration file can not be found, even if it invalid.
However, when user explicitly passes `--local` flag, that means
we can gracefully handle this error and continue. This commit does that
for the commands having `--local` flag.
Kubernetes-commit: ba49ccdbc9b4761d0c9589ab7ca9f41029a99568