Update trial page selectors to fix broken e2e tests

What does this MR do and why?

• free_trial_spec.rb broken on staging due to UI change !77537 (merged)
• Update trial/new page selectors to use data-qa-selector

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How to set up and validate locally

Run

bundle exec bin/qa Test::Instance::All https://staging.gitlab.com -- qa/specs/features/ee/browser_ui/11_fulfillment/purchase/free_trial_spec.rb

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