HPCC-11823 Improve efficiency of sorting archived wuid list

Used to be performing a linear walk of list so far and inserting.
Change to gather and post sort.

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
@wangkx - I couldn't see any reason/need to check isEmpty(w.getWuid()) .. which it no longer is in the sort method.
Please look/comment.