Add code suggestions contact sales to billing pages

What does this MR do and why?

• Adds code suggestions contact sales to billing pages as a card for more marking of code suggestions. Utilized a feature flag as per design in #421953 (closed)
  • trials and other non paid plans are excluded from this showing as per #421953 (closed)
  • feature flag is group/namespace based as per spec
• Extends the hand raise lead frontend/backend to allow the product_interaction to be configurable as per spec in #421953 (closed).
• Resolves a few rubocop exceptions on files touched.

Screenshots or screen recordings

note plans on gdk are more than exist in production

plan	Before	After
paid not ultimate
ultimate

How to set up and validate locally

note submitting the form will fail due to CustomersDot setup. Verification of that submission can be seen in ee/spec/features/billings/billing_plans_spec.rb and will be verified fully in staging.

1. Setup to simulate SaaS and restart GDK
2. Enable cs_connect_with_sales and check_namespace_plan in rails console
   • Feature.enable(:cs_connect_with_sales)
   • ApplicationSetting.first.update(check_namespace_plan: true)
3. Create a new top-level group.
4. Apply the premium plan to the group via rails console

group = Group.last
plan = Plan.find_by(name: 'premium')
group.gitlab_subscription.update(hosted_plan: plan)

5. Verify billing page (example: http://gdk.test:3000/groups/billing-code-suggestions-example-group/-/billings)
6. Apply the ultimate plan to the group via rails console

group = Group.last
plan = Plan.find_by(name: 'ultimate')
group.gitlab_subscription.update(hosted_plan: plan)

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 #421953 (closed)