Ansible is unable to update ssh known hosts when a non default SSH port is used

[Allain Legacy]

Brief Description
-----------------
The "Update SSH known hosts" task is using a regex that is not compatible with a custom SSH port. As a result it is not possible to remotely configure a node that now has an SSH key that differs from the previous installation.

  - name: Update SSH known hosts
    lineinfile:
      path: ~/.ssh/known_hosts
      state: absent
      regexp: '^{{ ansible_host }}'
    delegate_to: localhost

The regex line in the task should be changed to something similar to the following:

      regexp: '^{{ ansible_host }}|^\[{{ ansible_host }}\]:{{ ansible_port }}'

Severity
--------
Minor, manually editing the .ssh/known_hosts file to delete the line is a temporary workaround

Steps to Reproduce
------------------
Attempt to remotely configure a system using Ansible with a custom SSH port (i.e., thru a NAT). The target system must have an SSH key that differs from the one in the user's current ~/.ssh/known_hosts file.

Expected Behavior
------------------
Ansible should remove the entry from the ~/.ssh/known_hosts file even if the SSH Port is not 22.

Actual Behavior
----------------
Ansible fails to run the "Look for unmistakenly StarlingX package" task with this error:
TASK [prepare-env : Look for unmistakenly StarlingX package] *******************
fatal: [cpe-0]: UNREACHABLE! => {"changed": false, "msg": "SSH Error: data could not be sent to remote host \"yow-alegacy-vm2.wrs.com\". Make sure this host can be reached over ssh", "unreachable": true}

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

System Configuration
--------------------
Any

Branch/Pull Time/Commit
-----------------------
Private load rebased May 22

Last Pass
---------
Unknown

Timestamp/Logs
--------------
See above

Test Activity
-------------
Developer testing

[Ghada Khalil (gkhalil)]

Marking as release gating; medium priority given this is not a common config and there is a workaround

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/663755

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/663755
Committed: https://git.openstack.org/cgit/starlingx/config/commit/?id=014cff7f7ce2a0d6d5dabdc442ce260228dd47cd
Submitter: Zuul
Branch: master

commit 014cff7f7ce2a0d6d5dabdc442ce260228dd47cd
Author: Tee Ngo <email address hidden>
Date: Thu Jun 6 15:48:54 2019 -0400

    Handling of unconventional port number in playbook

    This commit supports unconventional port for ssh related tasks.
    It also eliminates a pesky warning caused by turning on pipelining.

    Closes-Bug: 1829051
    Closes-Bug: 1830258
    Change-Id: I8d1f054cdec8f2ed2a3f71b70ea10a1f7643831f
    Signed-off-by: Tee Ngo <email address hidden>