Update cloud_activation_spec to use license API

What does this MR do and why?

part of #366093 (closed)

• Add a delete all licenses via API step in before block to make sure the instance don't already have an active subscription
• Add API methods to EE::Resource::License class

Screenshots or screen recordings

Pipeline result - https://gitlab.com/gitlab-org/gitlab-qa-mirror/-/jobs/2652593650

How to set up and validate locally

Run locally:

bundle exec bin/qa Test::Instance::All http://127.0.0.1:3000 -- qa/specs/features/ee/browser_ui/11_fulfillment/license/cloud_activation_spec.rb

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.