Freeing sortgroupatts in use_physical_tlist

I was looking at the code in use_physical_tlist().

In the code block checking CP_LABEL_TLIST, I noticed that the Bitmapset sortgroupatts is not freed before returning from the method.

Looking at create_foreignscan_plan() (in the same file):

        bms_free(attrs_used);

It seems the intermediate Bitmapset is freed before returning.

I would appreciate review comments for the proposed patch.

Thanks