Optimize query for issue neighbors

What does this MR do and why?

This fixes slow queries when moving issues on an issue board.

This uses the technique / module described in https://docs.gitlab.com/ee/development/database/efficient_in_operator_queries.html

• Old query: https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/7491/commands/26655
• New query: https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/7491/commands/26652

Related to #345921 (closed)

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