chore: adding info to debug whenever headers are being skipped due to cors policy

[obecny]

Which problem is this PR solving?

• fixes Improve diagnostic logging for header injection from client instrumentations #2044

Short description of the changes

• It will debug information whenever adding headers was prevented because origin didn't match the config property propagateTraceHeaderCorsUrls

[codecov]

Codecov Report

Merging #2061 (657fe53) into main (a51bbbd) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 657fe53 differs from pull request most recent head b7cd485. Consider uploading reports for the commit b7cd485 to get more accurate results

@@           Coverage Diff           @@
##             main    #2061   +/-   ##
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  Coverage   93.07%   93.08%           
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  Files         154      154           
  Lines        5991     5999    +8     
  Branches     1256     1258    +2     
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+ Hits         5576     5584    +8     
  Misses        415      415           

Impacted Files	Coverage Δ
...s/opentelemetry-instrumentation-fetch/src/fetch.ts	99.27% <100.00%> (+0.02%)	⬆️
...emetry-instrumentation-xml-http-request/src/xhr.ts	96.89% <100.00%> (+0.06%)	⬆️

[MSNev]

Minor suggestion on the actual error content headers not injected vs headers inject skipped

And as a general diagnostic error logging (I know we have previously talked about adding a scope using a standard mechanism), but in the mean-time do we want to manually add the scope to make it easier for us and users to understand where this log cam from?

eg. (Using OT-Fetch as an example -- it probably needs a larger general discussion to define a general convention)
api.diag.debug('OT-Fetch: headers not injected due to CORS policy");

[obecny]

I think this is yet to be decided how the namespace should be constructed but not in this PR, please move the discussion to separate issue. With regards to copy it is how it was suggested in the raised issue.