acceptance: mark vector search endpoint tests as RequiresUnityCatalog (#5057)

## Summary
- Adds `RequiresUnityCatalog = true` to vector search endpoint
acceptance tests so they run against UC-enabled cloud environments.
- Added it to all VS tests (including `Cloud = false`) in case we make
them `Cloud = true` later

## Test plan
- [ ] CI acceptance tests pass
- [ ] Cloud run picks up the UC requirement correctly

This pull request and its description were written by Isaac.

Author: janniklasrose

acceptance/bundle/deployment/bind/vector_search_endpoint/out.test.toml

@@ -1,5 +1,6 @@
 Local = true
 Cloud = true
+RequiresUnityCatalog = true
 
 Ignore = [
     ".databricks",

acceptance/bundle/deployment/bind/vector_search_endpoint/test.toml

@@ -1,5 +1,6 @@
 Local = true
 Cloud = true
+RequiresUnityCatalog = true
 
 # Vector Search endpoints are only available in direct mode (no Terraform provider)
 EnvMatrix.DATABRICKS_BUNDLE_ENGINE = ["direct"]