E2E: Target Experimental Features Checkbox Within Permissions Settings

What does this MR do and why?

Fixes https://gitlab.com/gitlab-org/gitlab/-/issues/480538

A new GitLab Duo features section has been added to group settings that contains the Use experiment and beta GitLab Duo features checkbox, which also currently exists in the Permissions and group features section. This is because the new checkbox added to the GitLab Duo features section is currently in development behind a feature flag, and once that has been fully rolled out and tested, the checkbox will be removed from the old Permissions and group features section.

This is a temporary fix to resolve the ambiguous match errors in the test by targeting the use-experimental-features-checkbox within the permissions-settings element specifically. It makes use of the yield provided within the expand_content method.

A long term solution to use the new GitLab Duo features section checkbox will need to be worked on separately as part of https://gitlab.com/gitlab-org/gitlab/-/issues/480538

MR acceptance checklist

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

The test ee/browser_ui/10_govern/explain_this_vulnerability_spec.rb is currently only configured to run against live environments.

To run this test against Staging, set the following QA env variables. The values for these can be found in the Staging Quality Ops' group's CI/CD settings

export GITLAB_USERNAME=gitlab-qa
export GITLAB_PASSWORD=<secret>
export WEBDRIVER_HEADLESS=false
export GITLAB_QA_USER_AGENT=<secret>
export GITLAB_ADMIN_USERNAME=gitlab-qa-bot
export GITLAB_ADMIN_PASSWORD=<secret>
export GITLAB_QA_ACCESS_TOKEN=<secret>
export GITLAB_QA_ADMIN_ACCESS_TOKEN=<secret>
export QA_GITLAB_URL=https://staging.gitlab.com

Then, in your local GDK, cd qa, and run:

bundle exec rspec qa/specs/features/ee/browser_ui/10_govern/explain_this_vulnerability_spec.rb