Adds an empty state indicating no runner failures

What does this MR do and why?

Implements #413102 (closed)

Add an empty state indicating that there are no runner failures and instance runners are healthy in the runners dashboard.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. This is GitLab Ultimate feature, ensure your instance in set up for this.
2. Enable feature flag for the dashboard Feature.enable(:runners_dashboard)
3. Visit the Admin -> Runner and select "Fleet Dashboard"

If you have some job failures, you can modify the following to force the empty state:

diff --git a/ee/app/assets/javascripts/ci/runner/components/runner_job_failures.vue b/ee/app/assets/javascripts/ci/runner/components/runner_job_failures.vue
index f58e2b355bc5..cf40ca43341a 100644
--- a/ee/app/assets/javascripts/ci/runner/components/runner_job_failures.vue
+++ b/ee/app/assets/javascripts/ci/runner/components/runner_job_failures.vue
@@ -27,7 +27,7 @@ export default {
       query: runnerFailedJobsQuery,
       fetchPolicy: fetchPolicies.NETWORK_ONLY,
       update({ jobs }) {
-        return jobs?.nodes || [];
+        return [];
       },
       error(error) {
         createAlert({ message: I18N_FETCH_ERROR });

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 #413102 (closed)