refactor(orbit): remove REST schema, status, and query templates routes

What does this MR do and why?

This MR removes four Orbit REST routes. GraphQL fields on Query.orbit replace them, and the web UI already uses those fields.

Removed route	Replacement
GET /api/v4/orbit/schema	Query.orbit.schema
GET /api/v4/orbit/schema/format	None. The route was hidden.
GET /api/v4/orbit/status	Query.orbit.serviceStatus
GET /api/v4/orbit/query/templates	Query.orbit.queryTemplates

The REST routes accepted ai_workflows tokens. Query.orbit.schema already accepts them. This MR gives serviceStatus and queryTemplates the same scope, so those tokens keep their access.

Changes

• ee/lib/api/orbit/data.rb: remove the four routes and the helper that only they used.
• GrpcClient#get_graph_schema and #get_cluster_health: remove the format: argument. Only the removed routes sent the LLM format.
• Remove the specs and docs of the removed routes. Regenerate the OpenAPI file, the route list, and the fine-grained token docs.

Effect on clients

• The Orbit CLI v0.160.0 and earlier calls REST schema and status. Those commands fail after this MR. The next CLI uses GraphQL first and REST as a fallback.
• The GraphQL fields do not return the llm text format or user.available.
• The four paths now return 404 Not Found.

References

• Removal plan: gitlab-org/orbit/knowledge-graph#263
• graph_status removal: !264745 (merged)
• GraphQL-first CLI base: gitlab-org/orbit/knowledge-graph!3085 (merged)
• Orbit API docs: !265619 (merged) stacks on this MR. Both MRs change doc/api/orbit.md and the generated files. The MR that merges second rebases and runs the generators again.

Screenshots or screen recordings

None. This MR has no UI change.

How to set up and validate locally

1. Run bin/rspec ee/spec/requests/api/orbit/ ee/spec/requests/api/graphql/analytics/orbit/.
2. Send GET /api/v4/orbit/status with a personal access token. The response is 404 Not Found.

MR acceptance checklist

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