docs(self-managed): fix the removal date of the deprecated keys

[aabouzaid]

Description

We have postponed the removal date of the deprecated keys, but the date wasn't changed for all documents.

When should this change go live?

• This is a bug fix, security concern, or something that needs urgent release support.
• This is already available but undocumented and should be released within a week.
• This on a specific schedule and the assignee will coordinate a release with the DevEx team. (apply hold label or convert to draft PR)
• This is part of a scheduled alpha or minor. (apply alpha or minor label)
• There is no urgency with this change and can be released at any time.

PR Checklist

• My changes are for an already released minor and are in /versioned_docs directory.
• My changes are for the next minor and are in /docs directory (aka /next/).

• My changes require an Engineering review, and I've assigned the Engineering DRI or delegate.
• My changes require a technical writer review, and I've assigned @camunda/tech-writers as a reviewer.

[conceptualshark]

Approving this, but also wondering if the reference in Announcements could use an update as well: https://docs.camunda.io/docs/next/reference/announcements/#syntax-changes-in-helm-chart

[jessesimpson36]

I read the changes thinking they were editing the readme of the helm repo. I'm re-reviewing knowing that this will be in the docs.camunda.io site.

[jessesimpson36]

Ok, looks good