Add ops feature flags for search curation inclusion

What does this MR do and why?

Adds feature flags to toggle which indices should be added to search index curation list.

These are related MRs to this process:

• Add dry run capability: !103959 (merged)
• Add inclusion parameter to support excluding everything besides specified indices: !103951 (merged)
• Add feature flags to toggle which indices should be added to inclusion parameter: !104423 (merged) 👈
• Add an ops feature flag that toggles dry_runparameter in Search::IndexCurationWorker: !104321 (merged)

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How to set up and validate locally

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MR acceptance checklist

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