Cherry-pick #8179 into v1.71.x

[arjan-bal]

Original PR: #8179
Related issue: #8173

RELEASE NOTES:

• resolver: EndpointMap's Get, Set and Delete operations are now O(1) on average.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.17%. Comparing base (8d46b21) to head (c20fb3e).
Report is 2 commits behind head on v1.71.x.

Additional details and impacted files

@@             Coverage Diff             @@
##           v1.71.x    #8184      +/-   ##
===========================================
- Coverage    82.39%   82.17%   -0.22%     
===========================================
  Files          387      387              
  Lines        38962    38944      -18     
===========================================
- Hits         32101    32004      -97     
- Misses        5555     5611      +56     
- Partials      1306     1329      +23     

Files with missing lines	Coverage Δ
resolver/map.go	96.19% <100.00%> (-0.56%)	⬇️

... and 27 files with indirect coverage changes

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