[release] Core stable release 1.14.0 updates

[otelbot-dotnet]

Note: This PR was opened automatically by the post-release workflow.

Merge once packages are available on NuGet and the build passes.

Changes

• Sets OTelLatestStableVer in Directory.Packages.props to 1.14.0.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.80%. Comparing base (22f7b8e) to head (dbd7b12).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6689      +/-   ##
==========================================
+ Coverage   86.72%   86.80%   +0.08%     
==========================================
  Files         258      258              
  Lines       11958    11958              
==========================================
+ Hits        10370    10380      +10     
+ Misses       1588     1578      -10     

Flag	Coverage Δ
unittests-Project-Experimental	86.62% <ø> (-0.07%)	⬇️
unittests-Project-Stable	86.70% <ø> (+0.26%)	⬆️
unittests-Solution	86.44% <ø> (-0.22%)	⬇️
unittests-UnstableCoreLibraries-Experimental	86.43% <ø> (+0.36%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 5 files with indirect coverage changes