Handle orphaned zoekt indices

What does this MR do and why?

The state management in introduced in this MR will help us remove orphaned indices. This is part of the effort in this epic: &14886 (closed)

New Scopes Query Plans

Search::Zoekt::Index.should_be_marked_as_orphaned

SELECT "zoekt_indices".* FROM "zoekt_indices" WHERE ("zoekt_indices"."zoekt_enabled_namespace_id" IS NULL OR "zoekt_indices"."zoekt_replica_id" IS NULL) AND "zoekt_indices"."state" NOT IN (230, 240)

https://postgres.ai/console/gitlab/gitlab-production-main/sessions/31375/commands/97385

Search::Zoekt::Index.should_be_deleted

SELECT "zoekt_indices".* FROM "zoekt_indices" WHERE "zoekt_indices"."state" IN (230, 240)

https://postgres.ai/console/gitlab/gitlab-production-main/sessions/31375/commands/97386

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