Set wiki_redirection feature flag to default enabled

What does this MR do and why?

Set :wiki_redirection feature flag to default enabled:

• Feature flag rollout issue: [Feature flag] Rollout of wiki_redirection (#460097)
• Feature issue: Support redirecting wiki pages to new URL on re... (#257892 - closed)
• Feature MRs:
  • Redirect wiki pages on renaming them (!150727 - merged)
  • Allow redirecting wiki directories on rename (!153289 - merged)

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