otelgin: Using c.FullPath() to set http.route attribute

[NeoCN]

As spanName can be custumized with SpanNameFormatter, so the spanName may not be the same with http.route, e.g. the spanName can be GET /users/:id, but the http.route is /users/:id, so, using c.FullPath() to set http.route attribute in otelgin

[linux-foundation-easycla]

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• ✅ login: NeoCN / name: Jason Ma (721e216, 9ed7145, 14d182a)

[dmathieu]

Could you add a test, as well as a changelog entry?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.8%. Comparing base (1ddc6ac) to head (14d182a).

❗ Current head 14d182a differs from pull request most recent head 9ed7145

Please upload reports for the commit 9ed7145 to get more accurate results.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5732   +/-   ##
=====================================
  Coverage   63.8%   63.8%           
=====================================
  Files        194     194           
  Lines      12238   12236    -2     
=====================================
- Hits        7818    7817    -1     
  Misses      4197    4197           
+ Partials     223     222    -1     

Files	Coverage Δ
...ation/github.com/gin-gonic/gin/otelgin/gintrace.go	81.1% <100.0%> (+0.8%)	⬆️

[NeoCN]

@dmathieu Done.

[dmathieu]

This changes the public API, and isn't what the PR describes. It should be its own PR.

[NeoCN]

OK, I will create two PR for those changes.

[NeoCN]

#5734 created for http.route change. @dmathieu