test_runner: Update database ids to be human readable.
test_runner: Update database ids to be human readable.

Before the Django 2.x upgrade, the DatabaseCreation
argument took an integer value.  To deal with running
mulitple test instances, we created a random start
range that could count up 100 workers until the next
random id.  Arbitrarily limiting the number of workers
to 100.

Post upgrade, we can now use string values. Enabling
the database + worker numbers to be more readable, as
well as removing the cap on the worker count.

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