LU-16331 utils: fix 'lfs find -O <uuid>' with gaps

LU-16331 utils: fix 'lfs find -O <uuid>' with gaps

Fix the UUID parsing in llapi_get_target_uuids() so that the OST
UUIDs are put into the right slots when there is a gap in numbering.
Otherwise, "lfs find -O <uuid>" will not be able to find the given
UUID if it is the first OST after the gap.

Add test case for 'lfs find' and 'lfs getstripe' with large/sparse
OST indices in conf-sanity test_81.

Test-Parameters: trivial testlist=conf-sanity env=ONLY="81-82"
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: Ia0581f85f016c202514148114924509118a0f792
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49207
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Feng Lei <flei@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>