Remove deprecated SNSAttributeSetter function in otelaws

[hostejulien]

This pull request removes the deprecated SNSAttributeSetter function from the otelaws package.

Related Issue: Closes #7097

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: hostejulien / name: Julien Hoste (880e2c9, 90c9275, 3497e45, 953c11d)
• ✅ login: MrAlias / name: Tyler Yahn (761b61a)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.8%. Comparing base (ae71e3e) to head (761b61a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #7136     +/-   ##
=======================================
- Coverage   75.8%   75.8%   -0.1%     
=======================================
  Files        207     207             
  Lines      19393   19391      -2     
=======================================
- Hits       14717   14714      -3     
  Misses      4243    4243             
- Partials     433     434      +1     

Files with missing lines	Coverage Δ
...hub.com/aws/aws-sdk-go-v2/otelaws/snsattributes.go	88.0% <ø> (+6.5%)	⬆️

... and 1 file with indirect coverage changes

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[MrAlias]

Looks good outside of the changelog entry fixes mentioned by @pellared. Thanks for the contribution!