fix: remove attributes from OTLPExporterConfigBase

[Flarna]

Which problem is this PR solving?

Fixes #2826

Short description of the changes

Remove the optional attributes property from OTLPExporterConfigBase because it's not part of the spec and it's actually not exported at all.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

existing tests

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

Merging #2991 (fac212c) into main (edf6157) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2991      +/-   ##
==========================================
- Coverage   92.77%   92.77%   -0.01%     
==========================================
  Files         183      183              
  Lines        6135     6134       -1     
  Branches     1300     1300              
==========================================
- Hits         5692     5691       -1     
  Misses        443      443              

Impacted Files	Coverage Δ
...erimental/packages/otlp-exporter-base/src/types.ts	16.66% <ø> (ø)
...ackages/otlp-exporter-base/src/OTLPExporterBase.ts	95.12% <100.00%> (-0.12%)	⬇️

[pichlermarc]

Thanks for removing this. 🙂 I must have glanced over that without noticing more than a hundred times. 😅