Add DB condition class tests

[WarLikeLaux]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues

What does this PR do?

Adds unit tests for 11 DB condition classes in yii\db\conditions that had zero test coverage.

Before

Tests: 0, Assertions: 0
Methods: 0% (0/47), Lines: 0% (0/79)
MSI: 0% (0/125 mutants killed)

After

Tests: 169, Assertions: 281
Methods: 100% (47/47), Lines: 100% (79/79)
MSI: 100% (125/125 mutants killed)

---

Changelog not required, because no source files changed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.13%. Comparing base (37b6e7b) to head (5bec93b).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #20767   +/-   ##
=========================================
  Coverage     80.13%   80.13%           
  Complexity    11533    11533           
=========================================
  Files           374      374           
  Lines         30206    30206           
=========================================
  Hits          24207    24207           
  Misses         5999     5999           

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

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.