Draft: Revert "Organization contains namespaces"

What does this MR do and why?

Organization contains namespaces (!120822 - merged) caused a deployment problem. We are reverting the MR to avoid chance of deployment problems for self managed customers.

Further to the MR revert

• Remove the namespaces.organization_id column if it exists
• No longer track Organization record deletions
• unprepare_async_index the namespaces.organization_id index

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Closes #412771 (closed)