E2E: Remove references to product analytics checkbox

What does this MR do and why?

E2E: Remove references to product analytics checkbox

Follow up to remove the product analytics checkbox which is no longer present. !147833 (comment 1844083709)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

The only spec that makes use of that path is configured to run against staging, so we can verify via:

QA_GITLAB_URL=https://staging.gitlab.com \
GITLAB_ADMIN_USERNAME=${GITLAB_ADMIN_USERNAME} \ 
GITLAB_ADMIN_PASSWORD=${GITLAB_ADMIN_PASSWORD} \
GITLAB_USERNAME=${GITLAB_USERNAME} \
GITLAB_PASSWORD=#{GITLAB_PASSWORD} \
GITLAB_QA_ADMIN_ACCESS_TOKEN=#{TOKEN} \
GITLAB_QA_ACCESS_TOKEN=#{TOKEN} \
GITLAB_QA_USER_AGENT=#{GITLAB_QA_USER_AGENT} \
bundle exec rspec qa/specs/features/ee/browser_ui/8_monitor/product_analytics/onboarding_spec.rb

At this moment in time this test isn't actually picked up by a job. After !149715 (merged) this will have different tags to run against.