[hail] [breaking] split_multi_hts: take previous GQ if PL is missing (#6172)
[hail] [breaking] split_multi_hts: take previous GQ if PL is missing (#6172)

* split_multi_hts: take previous GQ if PL is missing

* fixed docs

cseed/hail,hail-is/hail,hail-is/hail,danking/hail,hail-is/hail,danking/hail,danking/hail,danking/hail,cseed/hail,cseed/hail,hail-is/hail,cseed/hail,cseed/hail,danking/hail,danking/hail,cseed/hail,danking/hail,danking/hail,cseed/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,cseed/hail