Add group transfer hook for zoekt

What does this MR do and why?

Add group transfer hook for zoekt

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Make sure you have Advanced Search enabled
2. Enable zoekt by adding following lines in gdk.yml

zoekt:
  enabled: true

3. Run the following commands from rails console to enable zoekt for a specific namespace

::Feature.enable(:index_code_with_zoekt)
::Feature.enable(:search_code_with_zoekt)
zoekt_shard = ::Zoekt::Shard.find_or_create_by!(index_base_url: 'http://127.0.0.1:6080/', search_base_url: 'http://127.0.0.1:6090/')
namespace = Namespace.find_by_full_path("flightjs") # Some namespace you want to enable
::Zoekt::IndexedNamespace.find_or_create_by!(shard: zoekt_shard, namespace: namespace.root_ancestor)
::Feature.enable(:use_new_zoekt_indexer)

4. Now you have to do a group transfer, for that go to Settings > General > Advanced > Transfer Group
5. Then you can verify all the cases mentioned below by doing ls in gitlab-development-kit/zoekt-data/development/index
   • Transfer a non-indexed group to a non-indexed group you will observe no new data is being added.
   • Transfer a indexed group to a zoekt indexed group you will observe no new data is being added and all the old project data is at the same place.
   • Transfer a non-indexed group to a zoekt indexed group you will see that a new file(s) are added of format <project-id>_xxxxxxx.zoekt of the projects that are part of the group.
   • Transfer a zoekt indexed group to a non-indexed group you will see that the file(s) are deleted of format <project-id>_xxxxxxx.zoekt of the projects that are part of the group.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #389761 (closed)