Move create_hand_raise_lead route/action to a new controller

What does this MR do and why?

Moves hand raise lead creation to separate controller for overall reduction of complexity in the controller layer for trials.

Specs covering e2e can be found in the billing_plans_spec.rb

Screenshot/Recordings

local verification with customersDot setup

How to set up and validate locally

note covered in this spec

1. Setup to simulate SaaS and restart GDK
2. Allow local network connections
   • Make sure Admin > Settings > Network > Outbound requests is set like the below
3. Setup CustomersDot locally.
4. Navigate to any group you are owner of and go to Settings -> Billings
5. Click on 'Talk to an expert today'.
6. Fill out the form and submit.

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 #393970 (closed)