New game page: don't count contributors more than once

[suspect15]

On the game2 pages, contributors are counted for each category of contribution separate from being the set author even though they are the same person. This leads to a seemingly inaccurate number of contributors listed since the author is also counted again as a contributor.

As I see the below example, I think 3 people worked on the set, but that is not true.

Example implying 3 total contributors, suspect15 +2 more:

Upon closer inspection, there are only 2 contributors, suspect15 and lethauntic.

[wescopeland]

Thanks for reporting. Converted to an issue: #3812