fix(tests_suite_test.go): shortening the rand int
fix(tests_suite_test.go): shortening the rand int

app names can’t be longer than 24 chars:
https://github.com/deis/workflow/blob/master/rootfs/api/south_migrations
/0025_auto__chg_field_app_id.py#L13

deis/workflow,deis/workflow,deis/workflow