Add migration to remove the wiki docs from the main index

What does this MR do and why?

Since wikis are now moved to a separate index, the wiki documents from the main index can be removed.

Screenshots or screen recordings

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Before	After

How to set up and validate locally

Make sure Elasticsearch is enabled

1. Open the Rails console

bundle exec rails c

2. Run the following command

Elastic::DataMigrationService[20230724221548].send(:migration).migrate

4. Now check the wiki docs on the main index. It should not have any docs

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

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.

Competition time

~ 9 hours

Related to #336100 (closed)

Related to Delete all the wiki documents from main index (#407560 - closed)