This change allows mixing InitConfiguration/ClusterConfiguration with
JoinConfiguration in a single YAML file, by performing the following changes:
- Replace the explicit error in `DetectUnsupportedVersion` with a warning.
- Modify `NodeConfigFileAndDefaultsToInternalConfig` to use only
`JoinConfiguration`.
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>