Pod name is not visible in runner details page when using new runner registration workflow
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With the move to the new runner creation workflow, the runner description is only stored for the configuration in the server (`ci_runners` table), which is created either in the UI or through the `POST /user/runners` REST API. In the previous workflow, the Helm chart passed a description consisting of the pod name, which then allowed users to see the pod name in e.g. the runner details page:
| registration token | runner creation in UI |
| ------ | ------ |
| {width="800px"} | {width="800px"} |
To provide the same experience, we'd need to:
- Create a `description` column in the `ci_runner_machines` table, similar to the one in `ci_runners`.
- Pass the description used in `gitlab-runner register` back to the server to be incorporated in the `ci_runner_machines` table. Currently, the challenge is that the `ci_runner_machines` record is created in response to a `POST /runners/verify` API call, and it doesn't make sense to add a description in that API. The other API that triggers a creation of the `ci_runner_machines` record is the `POST /jobs/request` endpoint.
- Display the `ci_runner_machines` description in the runner manager rows, and possibly in other pages which are displaying the runner description.
Created from [user report](https://gitlab.com/gitlab-org/gitlab/-/issues/423020#note_1532207258).
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