Remove a trading pair from order book tracking.
This endpoint removes a trading pair from a connector’s order book tracker, cleaning up resources for pairs that are no longer needed.
Args: request: Request with connector name, trading pair, and optional account name
Returns: TradingPairResponse with success status and message
Raises: HTTPException: 500 if removal fails
Basic authentication header of the form Basic <encoded-value>, where <encoded-value> is the base64-encoded string username:password.