Adding setting the LOCALDOMAIN env variable to "" when updating host files.

[swade1987]

By default, the Go DNS resolution uses initially the server from /etc/resolv.conf file and not /etc/hosts.

The easiest option seems to be to add a LOCALDOMAIN environment variable to the apiserver container.

    env:
      - name: LOCALDOMAIN
        value: ""

Not having the above environment variable set has caused issues with customer installs in the past.

I feel it'd be useful for Kismatic to set this environment variable when in the plan file the update_hosts_files flag is set to true.

Reference: https://github.com/apprenda/kismatic/issues/485