Duplicate dns host-record should not be allowed using bootstrap config

[Joseph Vazhappilly]

Brief Description
-----------------
Ansible bootstrap allows to create multiple host records with same dns name and ip address successfully without error. Invalid DNS hostnames are getting created in /etc/hosts

Severity
--------
Minor

Steps to Reproduce
------------------
1. Configure user_dns_host_records to have duplicate
user_dns_host_records:
  host1: host,127.0.0.1
  host2: host,127.0.0.1
2. Run ansible bootstrap playbook as below
ansible-playbook /usr/share/ansible/stx-ansible/playbooks/bootstrap.yml
3. Check /etc/hosts file for duplicates

Expected Behavior
------------------
DNS host record with same name and ip should not be allowed.
Invalid host entries should not be allowed.

Actual Behavior
----------------
Creation of duplicate host records

Reproducibility
---------------
100%

System Configuration
--------------------
One node system

Branch/Pull Time/Commit
-----------------------
starlingx/master

Last Pass
---------
NA

Timestamp/Logs
--------------
NA

Test Activity
-------------
Feature Testing

Workaround
----------
NA

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/ansible-playbooks/+/907071

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/ansible-playbooks/+/907071
Committed: https://opendev.org/starlingx/ansible-playbooks/commit/57ba971e6d2b132030b8b052d81187b2fa350111
Submitter: "Zuul (22348)"
Branch: master

commit 57ba971e6d2b132030b8b052d81187b2fa350111
Author: Joseph Vazhappilly <email address hidden>
Date: Mon Jan 29 08:23:00 2024 -0500

    Update host record validation during bootstrap

    Ansible bootstrap playbook is updated to check and fail, if duplicate
    DNS host records or invalid hostnames are specified in the
    `user_dns_host_records` parameter.

    Closes-bug: 2051553

    Test Plan:
    PASS: Verify bootstrap playbook with duplicate host records
    PASS: Verify bootstrap playbook with valid & invalid hostname

    Change-Id: Icdfa1bb2b1866020964ef22efe5fbced10618ff8
    Signed-off-by: Joseph Vazhappilly <email address hidden>