fix(backend): MemoryKVCacheのキャッシュGC処理においてキャッシュが期限切れにならないことがある問題を修正

[samunohito]

What

タイトルの通りです。

Why

fix #15500

Additional info (optional)

テストを追加し、対応前の状態で流すとfailになること、対応後の状態で流すとpassになることを確認しています

Checklist

• Read the contribution guide
• Test working in a local environment
• (If needed) Add story of storybook
• (If needed) Update CHANGELOG.md
• (If possible) Add tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 15.14%. Comparing base (a75f3ad) to head (b9ee1e8).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #17512      +/-   ##
===========================================
- Coverage    24.87%   15.14%   -9.74%     
===========================================
  Files         1161      248     -913     
  Lines        39629    12412   -27217     
  Branches     11041     4218    -6823     
===========================================
- Hits          9859     1880    -7979     
+ Misses       23849     8241   -15608     
+ Partials      5921     2291    -3630     

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[github-actions]

このPRによるapi.jsonの差分
差分はありません。
Get diff files from Workflow Page

[github-actions]

Backend memory usage comparison

Before GC

Metric	base (MB)	head (MB)	Diff (MB)	Diff (%)
VmRSS	299.39 MB	307.92 MB	+8.53 MB	+2.85%
VmHWM	299.39 MB	307.92 MB	+8.53 MB	+2.85%
VmSize	23164.15 MB	23172.53 MB	+8.37 MB	+0.03%
VmData	1364.50 MB	1373.17 MB	+8.66 MB	+0.63%

After GC

Metric	base (MB)	head (MB)	Diff (MB)	Diff (%)
VmRSS	299.54 MB	307.93 MB	+8.38 MB	+2.79%
VmHWM	299.54 MB	307.93 MB	+8.38 MB	+2.79%
VmSize	23164.82 MB	23172.62 MB	+7.79 MB	+0.03%
VmData	1365.17 MB	1373.25 MB	+8.08 MB	+0.59%

After Request

Metric	base (MB)	head (MB)	Diff (MB)	Diff (%)
VmRSS	299.92 MB	308.47 MB	+8.54 MB	+2.84%
VmHWM	299.92 MB	308.47 MB	+8.54 MB	+2.84%
VmSize	23164.82 MB	23172.70 MB	+7.87 MB	+0.03%
VmData	1365.17 MB	1373.33 MB	+8.16 MB	+0.59%

See workflow logs for details