tmp directory won't be cleaned after udf query end

While using udf to query, and when the memory is not enough, we will spill the data to disk. However when  the query end, the tmp directory is not cleaned completely.

To replay, you can  use the UDF in the attachment, and  then create function with that. change the `udf_memory_budget_in_mb` to `0.01 `and  then insert 1000000 points data. After that,  you can use your registered udf to do the query.