refactor(backend): replace private-ip with ipaddr.js

[saschanaz]

What

タイトル通り

Why

#10938 でしゅいろさんがおごごごごしなくてすむように

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

Merging #11041 (975cc20) into develop (5d922e3) will increase coverage by 0.00%.
The diff coverage is 50.00%.

@@             Coverage Diff             @@
##           develop   #11041      +/-   ##
===========================================
  Coverage    77.42%   77.43%              
===========================================
  Files          739      907     +168     
  Lines        70493    91359   +20866     
  Branches      6449     6885     +436     
===========================================
+ Hits         54582    70744   +16162     
- Misses       15911    20615    +4704     

Impacted Files	Coverage Δ
packages/backend/src/core/DownloadService.ts	70.39% <44.44%> (+0.65%)	⬆️
packages/backend/src/misc/get-ip-hash.ts	78.57% <100.00%> (ø)

... and 169 files with indirect coverage changes

[syuilo]

🙏🙏🙏