[FE] Remove instance-level Value Stream Analytics

frontend portion of #223734 (closed)

Problem to solve

With #196455 (closed) we removed access to instance level value stream analytics from the top level navigation in favour of group level VSA. Currently VSA cannot be accessed via the navigation bar, but can be browsed to directly.

We should eliminate any remaining Instance-level VSA code to correctly reflect this.

User experience goal

We are moving analytics features to the group level, this will help clear up any possible confusion on how to access VSA. Additionally, the additional code and tests are starting to impact developing new features.

Proposal

• Remove the group selector from the VSA frontend code
• Update the VSA frontend vuex state to remove code related to selecting a group, since the group details are populated via data-* attributes from the backend
• Update related frontend specs