drafts: Rename `delete_id` to `draft_to_be_focused_id`.
drafts: Rename `delete_id` to `draft_to_be_focused_id`.

`delete_id` in `drafts.js` referred to the next draft row which was
to be focused when deleting using hot keys. The var name was absurd
and is hence renamed.

rishig/zulip,hackerkid/zulip,zulip/zulip,rht/zulip,punchagan/zulip,rht/zulip,kou/zulip,showell/zulip,zulip/zulip,hackerkid/zulip,timabbott/zulip,timabbott/zulip,zulip/zulip,hackerkid/zulip,eeshangarg/zulip,punchagan/zulip,tommyip/zulip,timabbott/zulip,showell/zulip,shubhamdhama/zulip,andersk/zulip,kou/zulip,eeshangarg/zulip,tommyip/zulip,rht/zulip,kou/zulip,eeshangarg/zulip,shubhamdhama/zulip,brainwane/zulip,showell/zulip,brainwane/zulip,andersk/zulip,shubhamdhama/zulip,timabbott/zulip,hackerkid/zulip,kou/zulip,synicalsyntax/zulip,hackerkid/zulip,timabbott/zulip,tommyip/zulip,rishig/zulip,zulip/zulip,rht/zulip,tommyip/zulip,andersk/zulip,brainwane/zulip,zulip/zulip,andersk/zulip,shubhamdhama/zulip,rishig/zulip,brainwane/zulip,showell/zulip,zulip/zulip,rht/zulip,timabbott/zulip,tommyip/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,punchagan/zulip,tommyip/zulip,brainwane/zulip,andersk/zulip,brainwane/zulip,rishig/zulip,synicalsyntax/zulip,rishig/zulip,punchagan/zulip,kou/zulip,kou/zulip,brainwane/zulip,hackerkid/zulip,hackerkid/zulip,shubhamdhama/zulip,showell/zulip,timabbott/zulip,showell/zulip,rishig/zulip,andersk/zulip,eeshangarg/zulip,tommyip/zulip,rht/zulip,showell/zulip,kou/zulip,synicalsyntax/zulip,rishig/zulip,eeshangarg/zulip,shubhamdhama/zulip,synicalsyntax/zulip,zulip/zulip,punchagan/zulip,shubhamdhama/zulip,synicalsyntax/zulip,synicalsyntax/zulip,synicalsyntax/zulip,rht/zulip,punchagan/zulip,andersk/zulip