Group and global search always go through zoekt replicas

What does this MR do and why?

Always search through zoekt replicas

Because there are no indices without a replica, we can safely switch over. This also fixes a bug where duplicate indices were returned from joins made first through namespaces instead of replicas.

Instead of making join through a namespace, we are doing a join on zoekt repositories to pinpoint which node a project is located on.

Query Plans

Before

https://postgres.ai/console/gitlab/gitlab-production-main/sessions/32388/commands/100047

After

https://postgres.ai/console/gitlab/gitlab-production-main/sessions/32388/commands/100046

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Before	After

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