leverage native async trait in PushMetricExporter

[gruebel]

Relates #2517

Changes

• also removed unused dependencies in sdk and stdout
• also migrated LogExporterWithFuture in the sdk bench to native async trait

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]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.1%. Comparing base (1aca212) to head (662d36f).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2662     +/-   ##
=======================================
- Coverage   79.1%   79.1%   -0.1%     
=======================================
  Files        120     120             
  Lines      22556   22562      +6     
=======================================
+ Hits       17857   17861      +4     
- Misses      4699    4701      +2     

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[cijothomas]

LGTM! Thank you.

[lalitb]

Thanks