Falling back to getting from db and recaching when cache is missing

What does this MR do and why?

Currently the cache can timeout during long imports, this causes issues as the database_id cannot be found anymore.

With this change, if the cache times-out, it will query the database for the id and re-cache it.

If there is no database_id, it caches -1 so avoids further calls to DB and returns nil instead

Screenshots or screen recordings

Screen Recording 2023-10-13 at 2.40.27 PM.mov

How to set up and validate locally

1. GitHub import should still work as expected
2. Can play around in rails console, Ensure the project you pass in has an issue with iid part of html_url attribute (42 in this case).

  api_response = {
    html_url: 'https://github.com/foo/bar/issues/42',
    user: { id: 44, login: 'alice' },
    body: 'Hello worlds',
    created_at: Time.now + 1.year,
    updated_at: Time.now + 1.year,
  }
   
  note = Gitlab::GithubImport::Representation::Note.from_api_response(api_response)
  finder = Gitlab::GithubImport::IssuableFinder.new(Project.last, note)
  # Now using a combination of 
  # finder.cache_database_id
  # Gitlab::Cache::Import::Caching.expire(finder.send(:cache_key), 1.second)

  # finder.database_id should return `nil` if issue is missing or cache has -1. Or the issue.id and re-caches it

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 #427097 (closed)