Geo Sites Status API - Remove deprecated wiki status data

What does this MR do and why?

Remove deprecated wiki status data from Geo Sites Status API. The wikis_* keys are superseded by project_wiki_repositories_* because this data type is migrated to use the Geo Self-Service Framework code.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

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.

Related issues

Related to #423114 (closed)