fix: sort partition, track size

[dkharms]

Description

We had several flaky tests:

• TestOldestMetrics;
• TestCapacityExceeded;
• TestFracInfoCache

They were flaky because we dropped the whole partition even if we drop more than necessary. And we dropped fractions of partition in random order.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.80%. Comparing base (23a344d) to head (02a5bee).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #536      +/-   ##
==========================================
- Coverage   76.88%   76.80%   -0.09%     
==========================================
  Files         248      248              
  Lines       18808    18810       +2     
==========================================
- Hits        14461    14447      -14     
- Misses       4347     4363      +16     

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[github-actions]

🔴 Performance Degradation

Some benchmarks have degraded compared to the previous run.
Click on Show table button to see full list of degraded benchmarks.

Show table

Name	Previous	Current	Ratio	Verdict
ESBulk-4	23a344	d11b49
	348.00 B/op	407.00 B/op	1.17	🔴