refactor(web-common): add incubating semconv to package

[pichlermarc]

Which problem is this PR solving?

Makes the package follow the rules as defined in the guidelines. Since @opentelemetry/semantic-conventions is now unpinned, we should not use the /incubating entry point.

Follows up on #5439

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.77%. Comparing base (4f91c1d) to head (fe6128a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5446   +/-   ##
=======================================
  Coverage   94.77%   94.77%           
=======================================
  Files         308      309    +1     
  Lines        7966     7967    +1     
  Branches     1678     1678           
=======================================
+ Hits         7550     7551    +1     
  Misses        416      416           

Files with missing lines	Coverage Δ
...ckages/web-common/src/SessionLogRecordProcessor.ts	100.00% <100.00%> (ø)
...al/packages/web-common/src/SessionSpanProcessor.ts	100.00% <100.00%> (ø)
experimental/packages/web-common/src/semconv.ts	100.00% <100.00%> (ø)