Enable dependency_list_vulnerabilities by default

What does this MR do?

This enables the dependency_list_vulnerabilities feature flag by default, making the feature defined in #10077 (closed) available by default.

The issue tracking this is MR is #12608 (closed).

Note: WIP, since it's blocked by #13190 (closed) and !15125 (merged).

Documentation is tracked by #12986 (closed).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• [-] Style guides
• Separation of EE specific content

Performance and testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers