Bug fix: Changes to `ComplexityException` error reverted

Changes to the ComplexityException error's structure and error code were reverted to their original format. Check out the example below:

{
    "error_code": "ComplexityException",
    "status_code": 429,
    "error_message": "Complexity budget exhausted, query cost 30001 budget remaining 19986 out of 1000000 reset in 3 seconds",
    "error_data": {},
    "errors": [
        "Complexity budget exhausted, query cost 30001 budget remaining 19986 out of 1000000 reset in 3 seconds"
    ],
    "account_id": 1234567890
}