Moves VulnerabilitiesHelper to FOSS - [RUN AS-IF-FOSS]

What does this MR do?

Moves VulnerabilitiesHelper to FOSS.

This helper was on EE and was being referenced by a CE class breaking FOSS master. Moving the helper and the associated spec to FOSS fixes the problem

Related to #292839 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content