Draft: Adds backfill for Ci Catalog on project

What does this MR do and why?

Backfills the ci_catalog and readme_content fields for Project

Screenshots or screen recordings

Coming soon to a screen near you

How to set up and validate locally

Using a project that has readme content, do the following in rails c:

project = Project.find(23)
client = Gitlab::Search::Client.new
client.update(index: Project.__elasticsearch__.index_name, id: project.es_id,
                      body: { doc: { readme_content: project.repository.readme&.data } })

This will update the readme_content for that project.

Verify that the project shows up in the search:

# where `readme content` is the search query
Gitlab::Elastic::SearchResults.new(user, 'readme content', Project.pluck(:id)).objects('projects')
=> [#<Project id:23 root/ci-componentss>>]

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.

Resolves: #411609 (closed)