common: Specify ansible_user var for local playbook run

[szczepax]

Ansible_user is undefined on Localhost with local connection and needs to be always passed with --extra-vars
https://radeksprta.eu/posts/ansible_user-is-undefined-on-localhost/

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This change is 

[osalyk]

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @szczepax)

[janekmi]

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @szczepax)

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utils/ansible/README.md line 116 at r1 (raw file):

For localhost execution with a local connection you should always pass `ansible_user=pmdkuser` as a variable due to
[ansible_user Is Undefined on Localhost](https://radeksprta.eu/posts/ansible_user-is-undefined-on-localhost/).

Learned the hard way. But knowing that it is just how it works no mystery remains. If you would like to link something I prefer to link the official documentation. Even though it is not easy to read.

My suggestion is below. No links. Rather an explanation of what is the deal.

Suggestion:

It is possible to run playbooks directly on the target platform. In this case, you have to always pass `ansible_user=pmdkuser` as an additional variable since the playbooks are fine-tuned for remote execution and assume the `ansible_user` variable is defined. When running on a remote target the connection plugin does it for you.

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utils/ansible/README.md line 144 at r1 (raw file):

Example - GitHub self-hosted runner setup

No additional variables below this point. This variable is local-specific whereas the example is generic.

[szczepax]

Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @janekmi)

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utils/ansible/README.md line 116 at r1 (raw file):

Previously, janekmi (Jan Michalski) wrote…

Learned the hard way. But knowing that it is just how it works no mystery remains. If you would like to link something I prefer to link the official documentation. Even though it is not easy to read.

My suggestion is below. No links. Rather an explanation of what is the deal.

Done.

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utils/ansible/README.md line 144 at r1 (raw file):

Previously, janekmi (Jan Michalski) wrote…

No additional variables below this point. This variable is local-specific whereas the example is generic.

ansible_user=pmdkuser is needed by "Create new namespace configuration" step

[grom72]

Continue on #6055