Use fewer messages in test_num_unread_for_subject().
Use fewer messages in test_num_unread_for_subject().

I am not sure why I originally coded this to use 10000
messages, since it's not really a performance test.

jphilipsen05/zulip,zulip/zulip,punchagan/zulip,jrowan/zulip,brainwane/zulip,dhcrzf/zulip,tommyip/zulip,synicalsyntax/zulip,showell/zulip,shubhamdhama/zulip,SmartPeople/zulip,shubhamdhama/zulip,mahim97/zulip,vabs22/zulip,rishig/zulip,vaidap/zulip,hackerkid/zulip,rishig/zulip,rht/zulip,rishig/zulip,kou/zulip,showell/zulip,rht/zulip,jphilipsen05/zulip,verma-varsha/zulip,shubhamdhama/zulip,brockwhittaker/zulip,kou/zulip,Galexrt/zulip,kou/zulip,vabs22/zulip,rishig/zulip,amanharitsh123/zulip,SmartPeople/zulip,shubhamdhama/zulip,punchagan/zulip,brockwhittaker/zulip,andersk/zulip,vaidap/zulip,ryanbackman/zulip,jackrzhang/zulip,rishig/zulip,shubhamdhama/zulip,andersk/zulip,j831/zulip,rht/zulip,amanharitsh123/zulip,vaidap/zulip,mahim97/zulip,jphilipsen05/zulip,brockwhittaker/zulip,kou/zulip,timabbott/zulip,SmartPeople/zulip,ryanbackman/zulip,punchagan/zulip,andersk/zulip,amanharitsh123/zulip,jrowan/zulip,andersk/zulip,amanharitsh123/zulip,punchagan/zulip,jphilipsen05/zulip,dhcrzf/zulip,andersk/zulip,timabbott/zulip,amanharitsh123/zulip,dhcrzf/zulip,mahim97/zulip,jphilipsen05/zulip,SmartPeople/zulip,zulip/zulip,Galexrt/zulip,j831/zulip,vabs22/zulip,jrowan/zulip,eeshangarg/zulip,jackrzhang/zulip,tommyip/zulip,dhcrzf/zulip,jackrzhang/zulip,dhcrzf/zulip,ryanbackman/zulip,mahim97/zulip,showell/zulip,jrowan/zulip,brainwane/zulip,brainwane/zulip,rishig/zulip,brainwane/zulip,punchagan/zulip,shubhamdhama/zulip,hackerkid/zulip,christi3k/zulip,vabs22/zulip,brockwhittaker/zulip,rht/zulip,brockwhittaker/zulip,synicalsyntax/zulip,vaidap/zulip,hackerkid/zulip,verma-varsha/zulip,j831/zulip,timabbott/zulip,hackerkid/zulip,showell/zulip,shubhamdhama/zulip,rht/zulip,hackerkid/zulip,zulip/zulip,amanharitsh123/zulip,tommyip/zulip,jackrzhang/zulip,j831/zulip,Galexrt/zulip,j831/zulip,showell/zulip,eeshangarg/zulip,vabs22/zulip,vabs22/zulip,tommyip/zulip,christi3k/zulip,brainwane/zulip,SmartPeople/zulip,Galexrt/zulip,j831/zulip,christi3k/zulip,Galexrt/zulip,jphilipsen05/zulip,verma-varsha/zulip,verma-varsha/zulip,ryanbackman/zulip,zulip/zulip,kou/zulip,ryanbackman/zulip,christi3k/zulip,showell/zulip,jackrzhang/zulip,timabbott/zulip,hackerkid/zulip,brockwhittaker/zulip,dhcrzf/zulip,dhcrzf/zulip,jrowan/zulip,kou/zulip,eeshangarg/zulip,timabbott/zulip,synicalsyntax/zulip,showell/zulip,Galexrt/zulip,verma-varsha/zulip,vaidap/zulip,mahim97/zulip,rishig/zulip,zulip/zulip,christi3k/zulip,hackerkid/zulip,andersk/zulip,tommyip/zulip,jackrzhang/zulip,brainwane/zulip,vaidap/zulip,eeshangarg/zulip,verma-varsha/zulip,rht/zulip,tommyip/zulip,andersk/zulip,mahim97/zulip,tommyip/zulip,synicalsyntax/zulip,zulip/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,ryanbackman/zulip,zulip/zulip,jrowan/zulip,synicalsyntax/zulip,timabbott/zulip,timabbott/zulip,brainwane/zulip,christi3k/zulip,synicalsyntax/zulip,Galexrt/zulip,kou/zulip,synicalsyntax/zulip,eeshangarg/zulip,rht/zulip,jackrzhang/zulip,punchagan/zulip,SmartPeople/zulip