Fix dismissed vulnerability mr widget spec selector

What does this MR do and why?

Fixes the below selector error which is happening on latest master currently

Unable to find css "[data-testid=\"dismissal_reason_listbox\"],[data-testid=\"dismissal-reason-listbox\"],[data-qa-selector=\"dismissal_reason_listbox\"],.qa-dismissal-reason-listbox"

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Before	After

How to set up and validate locally

WEBDRIVER_HEADLESS=false GITLAB_ADMIN_PASSWORD="XXXX" GITLAB_QA_ACCESS_TOKEN=XXXXX GITLAB_PASSWORD="XXXXX" QA_LOG_LEVEL=DEBUG QA_GITLAB_URL=http://192.168.86.46:3000 bundle exec rspec  ./qa/specs/features/ee/browser_ui/10_govern/dismissed_vulnerabilities_in_security_widget.rb

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.