`kubeadm upgrade plan` uses to support the configure of component
configs(kubeproxy and kubelet) in a config file and then check if
the version is supported or not, if it's not supported it will be
marked as a unsupported version and require to manually upgrade
the component.
This feature will make the upgrade config API much harder as this
violates the no-mutation principle for upgrade, and we have seen it's
quite problematic to do like this.
This change removes the support of configurable component configs for
`kubeadm upgrade plan`, along with the removal, the logic to parse
the config file to decide whether a manual upgrade for the component
configs is needed is removed as well.
NOTE that API is not changed, i.e. `ManualUpgradeRequired` is not removed
from `ComponentConfigVersionState` but it's no-op now.
Signed-off-by: Dave Chen <dave.chen@arm.com>
0786fcc941