#### Description
- Removes the deprecated `POST /api/v1/service_accounts/{id}/roles` and
`DELETE /api/v1/service_accounts/{id}/roles/{rid}` routes, their HTTP
handlers, and the `DeprecatedPostableServiceAccountRole` type, now that
all consumers use `/api/v1/service_account_roles`.
- Keeps the `GET /api/v1/service_accounts/{id}/roles` listing endpoint.
- Regenerates `docs/api/openapi.yml` and the frontend client.
#### Issues closed by this PR
Closes SigNoz/platform-pod#2919
#### Additional Information
- Final step of the migration; the frontend (#12589) and
integration-test (#12590) consumer moves are already merged.
dca6aa497d