Fix spec/frontend/design_management/pages/index_spec.js

This feature to be deprecated, so this tests can be ignored for now

Why are we doing this work

Remove describeSkipVue3, SkipReason and make test compatible both for Vue 2 and Vue 3

Relevant links

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

Verification steps