Tests: hardcode list of NLPModel problems

[adrhill]

Compared to a solution based on filtering blacklisted problems, hardcoding a whitelist should be more future-proof.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.16%. Comparing base (aed919e) to head (bb3c021).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #286      +/-   ##
==========================================
+ Coverage   89.92%   92.16%   +2.24%     
==========================================
  Files          30       30              
  Lines        1201     1200       -1     
==========================================
+ Hits         1080     1106      +26     
+ Misses        121       94      -27     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.