fix(backend): fix #16994 by approach 6

[kakkokari-gtyih]

What

• trustProxy のデフォルト値をループバック・ローカルIPに変更（⑥）
• trustProxy のコンフィグ設定に関する案内を強化
• リバースプロキシやCDNなどのより上流のレイヤでレートリミットを制御したい場合や、緊急時の緩和策としてdisableIpRateLimit設定を追加（デフォルト false - Misskey内部でのIPアドレスレートリミットは有効）

Why

Fix #16994

Additional info (optional)

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 13.96%. Comparing base (d35ddc7) to head (acd79f8).
⚠️ Report is 12 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff              @@
##           develop   #17005       +/-   ##
============================================
- Coverage    62.83%   13.96%   -48.88%     
============================================
  Files         1150      237      -913     
  Lines       115242    11281   -103961     
  Branches      7896     3731     -4165     
============================================
- Hits         72409     1575    -70834     
+ Misses       40690     7584    -33106     
+ Partials      2143     2122       -21     

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[github-actions]

Backend Memory Usage Comparison

Metric	base	head	Diff
RSS	358.80 MB	352.80 MB	-5.99 MB (-1.67%)

See workflow logs for details

[github-actions]

このPRによるapi.jsonの差分
差分はありません。
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[kakkokari-gtyih]

ci通った