docs(sm): add troubleshooting on k8s issues affecting zeebe

[Langleu]

Description

Related to a Support case on Slack and Jira.

It's an addition to the troubleshooting page as an infrastructure-related problem can cause issues with Zeebe, and it may seem like Zeebe is the culprit.

Theoretically, it can happen for any Zeebe version, as it depends on the Infrastructure. I've added it to the troubleshooting page for self-managed, which exists since 8.5.

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.

[Langleu]

TIL: gh: Projects cannot have more than 1200 items. To add more, please archive or delete existing items.

[akeller]

TIL: gh: Projects cannot have more than 1200 items. To add more, please archive or delete existing items.

Happy to share how you can also overachieve hit this limit 😭 🤣