remove_default_searchdomains inconsistent default value

[yckaolalala]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #9948

Special notes for your reviewer:

when remove_default_searchdomains is undefined

# remove_default_searchdomains: false

In ansible, default value is false .

- name: set default dns if remove_default_searchdomains is false
  set_fact:
    default_searchdomains: ["default.svc.{{ dns_domain }}", "svc.{{ dns_domain }}"]
  when: not remove_default_searchdomains|default()|bool or (remove_default_searchdomains|default()|bool and searchdomains|default([])|length==0)

In Jinja, if undefined, it does not match remove_default_searchdomains is sameas false, and the default value is true.

{% if remove_default_searchdomains is sameas false or (remove_default_searchdomains is sameas true and searchdomains|default([])|length==0)%}
Domains={{ ([ 'default.svc.' + dns_domain, 'svc.' + dns_domain ] + searchdomains|default([])) | join(' ') }}
{% else %}
Domains={{ searchdomains|default([]) | join(' ') }}
{% endif %}

Does this PR introduce a user-facing change?:

Correctly handle remove_default_searchdomains  when value is undefined

[k8s-ci-robot]

Hi @yckaolalala. Thanks for your PR.

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[yankay]

/ok-to-test

[yankay]

Thanks @yckaolalala for the PR
/lgtm

[floryut]

@yckaolalala Thank you for the PR 👍

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: floryut, yckaolalala

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