Update selectors to use new kebab format

What does this MR do and why?

Related to: #421269 (closed)

Fixes qa/specs/features/ee/browser_ui/2_plan/analytics/value_stream_analytics_spec.rb:118 by updating a few selectors to the new kebab case format.

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Before	After

How to set up and validate locally

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

From the qa/ directory, run:

GITLAB_QA_ADMIN_ACCESS_TOKEN="<staging_admin_access_token>" GITLAB_QA_ACCESS_TOKEN="<staging_pat_for_gitlab_qa_user>" GITLAB_USERNAME=gitlab-qa GITLAB_PASSWORD=<staging_password_for_gitlab_qa> CHROME_HEADLESS=false bundle exec bin/qa Test::Instance::All https://staging.gitlab.com qa/specs/features/ee/browser_ui/2_plan/analytics/value_stream_analytics_spec.rb:118

MR acceptance checklist

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