Fix stdout traceexporter to show scope attributes

[cijothomas]

Fixes # Design discussion issue (if applicable) #

Changes

Please provide a brief description of the changes here.

Merge requirement checklist

• [ ] CONTRIBUTING guidelines followed
• [ ] Unit tests added/updated (if applicable)
• [ ] Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• [ ] Changes in public API reviewed (if applicable)

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 71.6%. Comparing base (348ec9e) to head (6d77643). Report is 26 commits behind head on main.

Files	Patch %	Lines
opentelemetry-stdout/src/common.rs	0.0%	1 Missing :warning:

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1747     +/-   ##
=======================================
+ Coverage   71.0%   71.6%   +0.5%     
=======================================
  Files        135     136      +1     
  Lines      20751   20845     +94     
=======================================
+ Hits       14746   14935    +189     
+ Misses      6005    5910     -95     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.