fix(opentelemetry-core): confusing log extract of composite propagator

[rv2673]

Which problem is this PR solving?

This fixes confusing diag logged warning in the composite propagator.

Short description of the changes

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

The existing test were used for checking for regression.

Checklist:

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

[linux-foundation-easycla]

• ✅login: rv2673 / (c1e33ad)

The committers listed above are authorized under a signed CLA.

[pichlermarc]

thanks for fixing this 👍

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.92%. Comparing base (f8ab559) to head (c1e33ad).
Report is 19 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5017      +/-   ##
==========================================
+ Coverage   93.39%   93.92%   +0.53%     
==========================================
  Files          46      310     +264     
  Lines         712     8138    +7426     
  Branches      120     1633    +1513     
==========================================
+ Hits          665     7644    +6979     
- Misses         47      494     +447     

Files with missing lines	Coverage Δ
...es/opentelemetry-core/src/propagation/composite.ts	100.00% <ø> (ø)

... and 265 files with indirect coverage changes