Tentative opentracing cleanup

[marcalff]

Fixes # (issue)

Changes

Please provide a brief description of the changes here.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[netlify]

❌ Deploy Preview for opentelemetry-cpp-api-docs failed.

Name	Link
🔨 Latest commit	1af418e
🔍 Latest deploy log	https://app.netlify.com/projects/opentelemetry-cpp-api-docs/deploys/683a2da4c53f1c0008c3fd96

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.86%. Comparing base (7a847ca) to head (1af418e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3454   +/-   ##
=======================================
  Coverage   89.86%   89.86%           
=======================================
  Files         212      212           
  Lines        6941     6941           
=======================================
  Hits         6237     6237           
  Misses        704      704           

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[marcalff]

Abandoned, to be reconsidered later.

Github downgraded cmake on utuntu 24.04 from 4.0.0 to 3.31.6, to there is no longer a pressing need to upgrade all the code base to CMake 4.0, which required cmake minimum version > 3.5 (opentracing uses 3.1, which breaks with CMake 4.0)