[repo] Cleanup shared code

[Kielek]

Related to open-telemetry/opentelemetry-dotnet-contrib#1806

Changes

Cleanup after

• moving shared tests to the contrib resporitory
• moving semantic convention to contrib repository. Keep only used attributes here.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• [ ] Appropriate CHANGELOG.md files updated for non-trivial changes
• [ ] Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.76%. Comparing base (6250307) to head (b30490f).
Report is 228 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5622      +/-   ##
==========================================
+ Coverage   83.38%   85.76%   +2.38%     
==========================================
  Files         297      254      -43     
  Lines       12531    11016    -1515     
==========================================
- Hits        10449     9448    -1001     
+ Misses       2082     1568     -514     

Flag	Coverage Δ
unittests	?
unittests-Solution-Experimental	85.38% <ø> (?)
unittests-Solution-Stable	85.75% <ø> (?)
unittests-Unstable-Core	19.77% <ø> (?)

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

see 115 files with indirect coverage changes

[reyang]

LGTM with some minor questions (non-blocking)

[rajkumar-rangaraj]

There was an early effort (#5432) to sync the shared files between opentelemetry-dotnet and opentelemetry-dotnet-contrib. We might either need to keep the files in sync or as Reiley recommended move these attributes to actual implementation.

[Kielek]

I think that this repository needs only small subset of full semantic convetion from contrib repository. We can move to actual implementation, but it could be more error prone (two copies of the same string). I would not expect frequent changes in attributes/resources needed in this repository (most of them already should be stable).