Adds an E2E spec to test scan execution policy pipeline flow

What does this MR do and why?

Relates to: gitlab-org/quality/quality-engineering/team-tasks#1914 (closed)

Tries to create a scheduled scan execution policy, similar to https://gitlab.com/gitlab-org/govern/security-policies/projects/test-cases/-/blob/main/dst/scan-execution-policies/023-enforce-project-level-can-execution-policy-to-enforce-scheduled-scan-for-chosen-branches-with-dast-scan-when-security-policy-project-is-not-linked-to-this-project.md

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

WEBDRIVER_HEADLESS=false GITLAB_QA_ACCESS_TOKEN=XXXX GITLAB_PASSWORD="XXXXX" QA_LOG_LEVEL=DEBUG QA_GITLAB_URL=http://172.30.0.158:3000 bundle exec rspec  ./qa/specs/features/ee/browser_ui/10_govern/scan_execution_policy_vulnerabilities_spec.rb

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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