Delete spans

## Authentication - API key: `Authorization: Bearer ` Request body: - is_deleting_all_logs (boolean, required if no filters; default false) - filters (object, required unless `is_deleting_all_logs` is true) Request (filters) example: ```json { "filters": { "status_code": { "operator": "eq", "value": 500 } } } ``` Request (delete all) example: ```json { "is_deleting_all_logs": true } ``` Response (200 OK): ```json { "message": "Logs are being removed from dataset in the background" } ``` Errors: - 400 Bad Request — neither `is_deleting_all_logs` nor `filters` provided - 404 Not Found — dataset not found or not in your organization