Disable usage of abuse_trust_scores table via feature flag

What does this MR do and why?

This change disables code paths that use the AntiAbuse::TrustScore code by adding a remove_trust_scores feature flag to disable this code path making it safer to follow-up with another MR to delete the code.

References

• #553436
• #574950

How to set up and validate locally

1. In rails console enable the feature flag

   Feature.enable(:remove_trust_scores)

2. Visit http://127.0.0.1:3000/
3. Register a new user
4. Delete that user
5. Tail the logs and background jobs to ensure deletion is working without error.

MR acceptance checklist

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