[wip] test: checkpoint dedup test

[zachschuermann]

What changes are proposed in this pull request?

test checkpoint dedup

How was this change tested?

test-only

[codecov]

Codecov Report

❌ Patch coverage is 81.81818% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.60%. Comparing base (5552d21) to head (059d5fe).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
kernel/src/checkpoint/log_replay.rs	81.81%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1279      +/-   ##
==========================================
- Coverage   83.60%   83.60%   -0.01%     
==========================================
  Files         107      107              
  Lines       25651    25662      +11     
  Branches    25651    25662      +11     
==========================================
+ Hits        21446    21455       +9     
  Misses       3135     3135              
- Partials     1070     1072       +2     

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