bugdown: Remove now-unnecessary short_names.
bugdown: Remove now-unnecessary short_names.

This field hasn't been used since we removed the related mention
syntax.

showell/zulip,rishig/zulip,rht/zulip,rht/zulip,Galexrt/zulip,showell/zulip,timabbott/zulip,amanharitsh123/zulip,timabbott/zulip,jackrzhang/zulip,timabbott/zulip,dhcrzf/zulip,rishig/zulip,kou/zulip,brainwane/zulip,tommyip/zulip,punchagan/zulip,kou/zulip,punchagan/zulip,rishig/zulip,synicalsyntax/zulip,andersk/zulip,dhcrzf/zulip,punchagan/zulip,andersk/zulip,showell/zulip,andersk/zulip,hackerkid/zulip,Galexrt/zulip,Galexrt/zulip,Galexrt/zulip,mahim97/zulip,synicalsyntax/zulip,rht/zulip,timabbott/zulip,showell/zulip,dhcrzf/zulip,brainwane/zulip,shubhamdhama/zulip,mahim97/zulip,showell/zulip,jackrzhang/zulip,synicalsyntax/zulip,tommyip/zulip,eeshangarg/zulip,jackrzhang/zulip,brainwane/zulip,dhcrzf/zulip,verma-varsha/zulip,punchagan/zulip,eeshangarg/zulip,shubhamdhama/zulip,hackerkid/zulip,showell/zulip,andersk/zulip,shubhamdhama/zulip,jackrzhang/zulip,brockwhittaker/zulip,timabbott/zulip,kou/zulip,synicalsyntax/zulip,brockwhittaker/zulip,zulip/zulip,kou/zulip,mahim97/zulip,mahim97/zulip,rht/zulip,jackrzhang/zulip,eeshangarg/zulip,tommyip/zulip,andersk/zulip,timabbott/zulip,mahim97/zulip,dhcrzf/zulip,brainwane/zulip,rishig/zulip,brockwhittaker/zulip,shubhamdhama/zulip,dhcrzf/zulip,tommyip/zulip,rht/zulip,Galexrt/zulip,hackerkid/zulip,hackerkid/zulip,kou/zulip,amanharitsh123/zulip,verma-varsha/zulip,amanharitsh123/zulip,punchagan/zulip,zulip/zulip,verma-varsha/zulip,tommyip/zulip,andersk/zulip,verma-varsha/zulip,synicalsyntax/zulip,rht/zulip,brockwhittaker/zulip,punchagan/zulip,eeshangarg/zulip,Galexrt/zulip,brainwane/zulip,brockwhittaker/zulip,shubhamdhama/zulip,verma-varsha/zulip,dhcrzf/zulip,hackerkid/zulip,amanharitsh123/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,showell/zulip,rishig/zulip,mahim97/zulip,jackrzhang/zulip,hackerkid/zulip,rishig/zulip,punchagan/zulip,brainwane/zulip,rht/zulip,brockwhittaker/zulip,zulip/zulip,kou/zulip,shubhamdhama/zulip,amanharitsh123/zulip,synicalsyntax/zulip,timabbott/zulip,tommyip/zulip,synicalsyntax/zulip,eeshangarg/zulip,andersk/zulip,eeshangarg/zulip,jackrzhang/zulip,eeshangarg/zulip,zulip/zulip,amanharitsh123/zulip,verma-varsha/zulip,shubhamdhama/zulip,rishig/zulip,tommyip/zulip,brainwane/zulip,Galexrt/zulip,zulip/zulip,zulip/zulip