Remove leftover commit documents from the main index

What does this MR do and why?

This MR will remove the leftover commit documents from the main index.

Screenshots or screen recordings

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Before	After

How to set up and validate locally

1. Open the rails console

bundle exec rails c

2. Populate commits in the main index

project = Project.last
::Gitlab::Search::Client.new.index(index: 'gitlab-development', routing: "project_#{project.id}", refresh: true,
    body: { commit: { type: 'commit',
        author: { name: 'F L', email: 't@t.com', time: Time.now.strftime('%Y%m%dT%H%M%S+0000') },
        committer: { name: 'F L', email: 't@t.com', time: Time.now.strftime('%Y%m%dT%H%M%S+0000') },
      rid: project.id, message: 'test' },
    join_field: { name: 'commit', parent: "project_#{project.id}" },
    repository_access_level: project.repository_access_level, type: 'commit',
  visibility_level: project.visibility_level })

project = Project.first
::Gitlab::Search::Client.new.index(index: 'gitlab-development', routing: "project_#{project.id}", refresh: true,
    body: { commit: { type: 'commit',
        author: { name: 'F L', email: 't@t.com', time: Time.now.strftime('%Y%m%dT%H%M%S+0000') },
        committer: { name: 'F L', email: 't@t.com', time: Time.now.strftime('%Y%m%dT%H%M%S+0000') },
      rid: project.id, message: 'test' },
    join_field: { name: 'commit', parent: "project_#{project.id}" },
    repository_access_level: project.repository_access_level, type: 'commit',
  visibility_level: project.visibility_level })

3. Ensure there is at least one commit in the main index by running the following curl command in bash

curl -XGET "http://localhost:9200/gitlab-development/_count" -H "kbn-xsrf: reporting" -H "Content-Type: application/json" -d'
{
  "query": {
    "bool": {
      "filter": [
        { "term": { "type": "commit" } }
      ]
    }
  }
}'

count should be greater than 0

4. Now run the following command in the rails console

 Elastic::DataMigrationService[20230911205548].send(:migration).migrate

5. Run again the curl command and ensure the count is 0

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.

Runtime

~ 141 minutes

[1] pry(main)> batch_size = 2_000
=> 2000
[2] pry(main)> throttle_delay = 3.minute
=> 3 minutes
[3] pry(main)> number_of_documents = 94076
=> 94076
[4] pry(main)> (number_of_documents / batch_size) * throttle_delay
=> 141 minutes

Related to #419781 (closed)