* optimize the implemention of k-selection on faiss gpu version
Signed-off-by: Ncmli <chengming.li@zilliz.com>

* update change log, re-classified the pr from feature to improvement
Signed-off-by: Ncmli <chengming.li@zilliz.com>

* update change log
Signed-off-by: Ncmli <chengming.li@zilliz.com>
Co-authored-by: Ncmli <chengming.li@zilliz.com>