REST: Deprecate runner details API fields

What does this MR do and why?

Description

Deprecate runner API fields

These no longer make sense since they can differ per runner manager (child entity).

See more in:

• REST API: RunnerDetails will no longer return v... (#457128)
• Audit GraphQL fields for ciRunner and evaluate ... (#411950 - closed)
• REST API: Runner will no longer return ip_address (#415159)
• Deprecate CiRunner fields duplicated in runner ... (#415185)

We're currently leaving these fields returning the same values (although from a different source). They will start returning null in %18.0.

Changelog: deprecated

Closes #457128

MR acceptance checklist

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After the change:

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Create a runner

2. Register it

3. Run the runner with gitlab-runner run so that we have a runner manager in the system

4. Find the ID of the runner and assign it to the RUNNER_ID environment var.

5. Run the following command against your GDK (you need to first create a personal token and assign it to GITLAB_GDK_TOKEN):

   curl --url "http://gdk.test:3000/api/v4/runners/$RUNNER_ID" --header "Authorization: Bearer $GITLAB_GDK_TOKEN" | jq