Fix the Starred Public Review Count for new user
    
The CounterField initializer for starred_public_request_count was calculating the count as 0 if the pk of that table was not null. The parantheses for this calculation was not setup properly , which caused the value to be setup as None for the first time user.
    
Also fixed a test which was assuming that the first time user will see None for the counts. With this and the associated djblets fix, this isnt true anymore.

This fixes the reviewboard side of things and is associated to the review request 3841 (which is a djblets fix)

Manual testing with localsites and regular ones.
Ran all reviewboard tests.