Add feature flag check for project VSD link

What does this MR do and why?

Disables the link to Value Streams Dashboards, when viewing Value Stream Analytics at the project level, unless the project_analytics_dashboard_dynamic_vsd feature flag is enabled.

Also ensures we always pass the namespace path to generateValueStreamsDashboardLink rather than the group path.

MR acceptance checklist

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How to set up and validate locally

Note: You will need an GitLab Ultimate license

1. Create a group with a single project in it
2. Create a custom value stream and navigate to the VSA page for the project
   • There should not be a link to Value Streams Dashboard on the page
3. Enable the project_analytics_dashboard_dynamic_vsd feature flag
4. Navigate back to the VSA page for the project, there should be a link to the Project Value Streams Dashboard page
5. Repeat for the group, but in this case the link will always be visible

Related to #454206 (closed)