Delete all x-ms-examples JSON files

[timotheeguerin]

Part of #4831.

RFC: https://github.com/Azure/azure-rest-api-specs/blob/rfc/unified-examples-format/documentation/rfc/unified-examples-format.md (§9 Phase 4)

Delete all legacy x-ms-examples JSON files from the repo — the new examples.yaml becomes the sole source of truth, with JSON generated on demand if still needed.

Scope

• Remove the per-version examples/*.json files across all services.
• Confirm no remaining consumer reads the JSON files directly (all joined via x-id).

Depends on #4840 (old example tooling disabled).