circle-docker: Simplify a bit for clarity and efficiency.
circle-docker: Simplify a bit for clarity and efficiency.

Install `jq` with APT -- that's a lot simpler to read than this
explicit download.

And coalesce several commands, following Docker upstream's
recommendation and avoiding unnecessary overhead.

rishig/zulip,showell/zulip,rht/zulip,jackrzhang/zulip,mahim97/zulip,shubhamdhama/zulip,kou/zulip,tommyip/zulip,rishig/zulip,brainwane/zulip,hackerkid/zulip,timabbott/zulip,synicalsyntax/zulip,zulip/zulip,hackerkid/zulip,eeshangarg/zulip,andersk/zulip,brainwane/zulip,kou/zulip,brainwane/zulip,synicalsyntax/zulip,rht/zulip,showell/zulip,eeshangarg/zulip,jackrzhang/zulip,rht/zulip,andersk/zulip,jackrzhang/zulip,eeshangarg/zulip,timabbott/zulip,rishig/zulip,dhcrzf/zulip,jackrzhang/zulip,brainwane/zulip,andersk/zulip,kou/zulip,dhcrzf/zulip,rishig/zulip,mahim97/zulip,synicalsyntax/zulip,jackrzhang/zulip,timabbott/zulip,mahim97/zulip,andersk/zulip,eeshangarg/zulip,rishig/zulip,hackerkid/zulip,punchagan/zulip,rht/zulip,timabbott/zulip,tommyip/zulip,tommyip/zulip,hackerkid/zulip,shubhamdhama/zulip,brainwane/zulip,shubhamdhama/zulip,shubhamdhama/zulip,rht/zulip,zulip/zulip,synicalsyntax/zulip,zulip/zulip,synicalsyntax/zulip,tommyip/zulip,punchagan/zulip,timabbott/zulip,mahim97/zulip,brainwane/zulip,tommyip/zulip,kou/zulip,showell/zulip,rishig/zulip,dhcrzf/zulip,eeshangarg/zulip,tommyip/zulip,shubhamdhama/zulip,punchagan/zulip,zulip/zulip,synicalsyntax/zulip,zulip/zulip,andersk/zulip,shubhamdhama/zulip,dhcrzf/zulip,hackerkid/zulip,zulip/zulip,dhcrzf/zulip,andersk/zulip,rht/zulip,timabbott/zulip,andersk/zulip,punchagan/zulip,eeshangarg/zulip,hackerkid/zulip,timabbott/zulip,zulip/zulip,eeshangarg/zulip,kou/zulip,showell/zulip,kou/zulip,showell/zulip,dhcrzf/zulip,rishig/zulip,jackrzhang/zulip,rht/zulip,dhcrzf/zulip,punchagan/zulip,showell/zulip,shubhamdhama/zulip,brainwane/zulip,jackrzhang/zulip,kou/zulip,showell/zulip,synicalsyntax/zulip,hackerkid/zulip,tommyip/zulip,punchagan/zulip,mahim97/zulip,punchagan/zulip,mahim97/zulip