core: use endpoint's uri for span's name

[woshilapin]

Before:

After:

Should much easier to dig through the traces of the endpoints. I just hope it works as expected for Datadog.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 29.14%. Comparing base (70e6bdc) to head (44e4bcc).
Report is 1 commits behind head on dev.

Files	Patch %	Lines
.../src/main/java/fr/sncf/osrd/cli/TkOpenTelemetry.kt	0.00%	3 Missing ⚠️
core/src/main/java/fr/sncf/osrd/cli/TkDataDog.kt	0.00%	2 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@             Coverage Diff              @@
##                dev    #7366      +/-   ##
============================================
+ Coverage     29.12%   29.14%   +0.02%     
  Complexity     2016     2016              
============================================
  Files          1141     1141              
  Lines        139912   139971      +59     
  Branches       2769     2769              
============================================
+ Hits          40744    40790      +46     
- Misses        97552    97565      +13     
  Partials       1616     1616              

Flag	Coverage Δ
core	76.29% <0.00%> (-0.03%)	⬇️
editoast	72.00% <ø> (+0.02%)	⬆️
front	9.36% <ø> (+<0.01%)	⬆️
gateway	2.43% <ø> (-0.01%)	⬇️
railjson_generator	87.49% <ø> (ø)
tests	83.96% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[eckter]

There's a formatting issue, other than that LGTM