cleanup: Use the structure as the key of the map instead of string

[novahe]

Ⅰ. Describe what this PR does

Use the structure as the key of the map instead of string

refer：
https://github.com/golang/groupcache/blob/41bb18bfe9da5321badc438f91158cd790a33aa3/lru/lru.go#L36-L37

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how to verify it

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[codecov]

Codecov Report

Merging #349 (1f269d7) into main (54ed9a5) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #349   +/-   ##
=======================================
  Coverage   64.85%   64.85%           
=======================================
  Files         116      116           
  Lines       11451    11451           
=======================================
  Hits         7426     7426           
  Misses       3440     3440           
  Partials      585      585           

Flag	Coverage Δ
unittests	64.85% <ø> (ø)

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[ZYecho]

thanks for your pr
please squash your commits

[novahe]

hi @ZYecho squashed it. PTAL~

[ZYecho]

/lgtm

[hormes]

/approve

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hormes

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[jasonliu747]

/lgtm