refactor(otelgin): refactor HTTP server attributes to use new semconv package

[flc1125]

closed #6764

[flc1125]

This PR has some duplicated (conflicting) content with #6747, and I'm resolving the conflicts after one of them is merged.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.5%. Comparing base (3d62c25) to head (65846f6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #6778   +/-   ##
=====================================
  Coverage   75.5%   75.5%           
=====================================
  Files        207     207           
  Lines      19149   19152    +3     
=====================================
+ Hits       14461   14475   +14     
+ Misses      4253    4241   -12     
- Partials     435     436    +1     

Files with missing lines	Coverage Δ
...ation/github.com/gin-gonic/gin/otelgin/gintrace.go	92.4% <100.0%> (+0.1%)	⬆️

... and 2 files with indirect coverage changes

[dmathieu]

I realize this gin has been missed here because there was no issue. I think there were none because the package was in the process of being removed when we planned the migration work.

[flc1125]

I realize this gin has been missed here because there was no issue. I think there were none because the package was in the process of being removed when we planned the migration work.

otelhttp is designed so well that gin can switch to the new one very quickly.