Fix small error in pp calculation

[int-y1]

According to the blog post, the bonus should only consider full ACs.

List of changes:

• Previously, Profile.problem_count was the number of problems with a positive score. Now, it's the number of problems with a full AC.
• Previously, the pp bonus includes partial ACs. Now, it excludes partial ACs.

Also, everything looked ok when I ran for x in Profile.objects.all(): x.calculate_points() in the shell.

[codecov-commenter]

Codecov Report

Base: 46.66% // Head: 46.66% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (f19a957) compared to base (7f62071).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2074      +/-   ##
==========================================
- Coverage   46.66%   46.66%   -0.01%     
==========================================
  Files         238      238              
  Lines       13247    13246       -1     
==========================================
- Hits         6182     6181       -1     
  Misses       7065     7065              

Impacted Files	Coverage Δ
judge/models/profile.py	81.97% <100.00%> (-0.08%)	⬇️

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[kiritofeng]

LGTM