Enable new wiki delete page RPC [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

This MR removes the feature flag gitaly_replace_wiki_delete_page enabling the new RPC to destroy wiki pages.

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

Related to #325526 (closed)