Optimize the `award_user_list` helper spec
According to
https://gitlab.com/gitlab-org/gitlab-ce/issues/23034#note_16586657, each
test for this helper generated 1,833 queries.
Now we only generate stubbed records, and only as many as we need for
each test.
This also corrects a slight logic bug in the helper itself. When the
number of awards was greater than the limit (9 by default), _and_ the
current user was one of them, we actually included 10 names, including
"You", plus the remaining count. Now we return the correct number
regardless.
See merge request !6722
212cf8f950