[Docs cleanup] API scenario testing docs

**Context:** API scenario testing (OAV) consumes the generated OpenAPI, so the tooling is still valid
Question: do we still need this tool or just make it archive?

**Tasks:**

- [ ] 🟡 `documentation/api-scenario/README.md` — "Swagger" → "generated OpenAPI"
- [ ] 🟡 `documentation/api-scenario/how-to/GenerateABasicApiScenario.md` — inputs are generated OpenAPI, not hand-authored Swagger
- [ ] 🟡 `documentation/api-scenario/how-to/MakeTestProxyRecording.md` — "Swagger consistency" → "OpenAPI consistency"
- [ ] 🟡 `documentation/api-scenario/how-to/QuickStart.md` — drop AutoRest/`readme.md`-tag dependency framing
- [ ] 🟡 `documentation/api-scenario/how-to/ResolveDependencies.md` — emphasize generated OpenAPI sources; clarify `readmeTag`
- [ ] 🟡 `documentation/api-scenario/references/ApiScenarioDefinition.md` — "Swagger operation/OperationId" → "OpenAPI"
- [ ] 🟡 `documentation/api-scenario/references/Runner.md` — replace AutoRest/`readme.md` config discovery with generated OpenAPI discovery
- [ ] 🟡 `documentation/api-scenario/references/ErrorCodeReference.md`
- [ ] 🟡 `documentation/api-scenario/references/Variables.md`
- [ ] 🟡 `documentation/api-scenario/references/v1.2/schema.json`