SYS-671 update wordpress helm chart - 6.9.1

[instantlinux]

Summary of Changes

• Upgrade wordpress to 6.9.1; adjust helm chart to mount only wp-content subdir, not the whole /var/www/html directory tree (but note that this may not be the way Wordpress publisher intends; they still expect the entire code directory to be kept in place through years of upgrades, to be updated by wp-admin itself: my copy had quite a few woefully outdated files).
• Update ansible/requirements.txt for pip 26.0 dependency
• A few other minor cleanups

Why is this change being made?

Routine security patching.

How was this tested? How can the reviewer verify your testing?

CI and local testing

Completion checklist

• The pull request is linked to all related issues
• This change has unit test coverage
• Documentation has been updated
• Dependencies have been updated and verified