populate_db: Fix stream colors being generated wrong.
populate_db: Fix stream colors being generated wrong.

Previously, the stream colors index i was accidentally a function only
of the user, so each user got the same color for all their streams.

This should provide a lot nicer-looking development environment
experience.

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