fix: ensure operation_id is always set on conn.private

[msutkowski]

There was an issue where you had to pass in the operationId on error cases to assert_operation_response because of the nature of the error handling halting and returning a collection of errors for the given step. Lifting the put_operation_id up gets around all of that as even if things halt, we'll still have a reference to the operationId in conn.private

[mbuhot]

Thanks @msutkowski !