streams: Fix counts using only one data point.
streams: Fix counts using only one data point.

We had the aggregation query for StreamCount done slightly wrong.

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