Enable admin runner read-only runner view

This change enables the runner_read_only_admin_view feature so
administrators can view the details of their runners.

This read-only view enhances runner admin capabilities by showing more
information about a runner that cannot be shown in the current edit
view.

Changelog: added

app/views/admin/runners/edit.html.haml

 - add_page_specific_style 'page_bundles/ci_status'
 
 - runner_name = "##{@runner.id} (#{@runner.short_sha})"
-- if Feature.enabled?(:runner_read_only_admin_view)
+- if Feature.enabled?(:runner_read_only_admin_view, default_enabled: :yaml)
   - breadcrumb_title _('Edit')
   - page_title _('Edit'), runner_name
   - add_to_breadcrumbs _('Runners'), admin_runners_path

config/feature_flags/development/runner_read_only_admin_view.yml

@@ -5,4 +5,4 @@ rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/350164
 milestone: '14.7'
 type: development
 group: group::runner
-default_enabled: false
+default_enabled: true