Add duo enterprise trial discover page

Related to #489072

What does this MR do and why?

Refactor the Trial discover page to use the ViewComponent framework introduced in !167945 (merged)

Similar to !168823 (merged)

MR acceptance checklist

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Before	After

How to set up and validate locally

1. Setup gdk to simulate SaaS - https://docs.gitlab.com/ee/development/ee_features.html#simulate-a-saas-instance and restart GDK

2. Sign in. Create new group

3. In rails console create / update new GitLab subscription for your new group

   bin/rails c
   namespace = Group.last
   gitlab_subscription = namespace.gitlab_subscription # find or create a new one if needed
   gitlab_subscription.update(hosted_plan: Plan.find_by(name: 'ultimate'))

4. Apply Duo Enterprise to the group

   bin/rails c
   add_on_purchase = GitlabSubscriptions::AddOnPurchase.create(subscription_add_on_id: GitlabSubscriptions::AddOn.find_by(name: 'duo_enterprise').id, namespace: Group.last, started_at: 55.days.ago, expires_on: (Date.today + 5.days), trial: true, quantity: 1, purchase_xid: '1', organization_id: 1)

5. Now go to /groups/your-group-name/-/discover