Add runner field to job_type

What does this MR do and why?

This MR adds a field runner to the GraphQL type job_type.rb

For context:

I'm refactoring the Admin > CI/CD > Jobs page from Haml to Vue (FF !98769 (merged)). Check out the before/after screenshots in the test implementation. The current job_type implementation doesn't include information about the runner used for the job, which I want to fix/add in this MR.

How to set up and validate locally

• run job_type_spec.rb
• run jobs_query_spec.rb

OR (Note that the screenshot or this approach has nothing to do with this MR. It is simply for demonstration purposes)

• Make sure to enable FF Feature.enable(:admin_jobs_vue)
• curl https://gitlab.com/TrueKalix/gitlab/-/raw/tempo/patches/pipeline_seed.patch | git apply
• seed pipeline data bundle exec rake db:seed_fu FILTER=14_pipelines
• curl https://gitlab.com/TrueKalix/gitlab/-/raw/tempo/patches/runner_cell_s.patch | git apply
• go to Admin > CI/CD > Jobs
• you should see runners like this

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.