fix(otlp-exporter-base): handle response error event

[pichlermarc]

Which problem is this PR solving?

See #6410, the error event on the response is unhandled, it may be triggered in certain cases, like the author describes. This PR fixes this by adding a test + handling the response. In these cases we should already have the headers, so I added handling for sucess/failure/retry based on that, even if the response was not fully received (since the response is not necessary to ensure the OTLP export remains functional)

Fixes #6410

Type of change

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

How Has This Been Tested?

• Added unit tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.59%. Comparing base (34e7d91) to head (f4bc454).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6412   +/-   ##
=======================================
  Coverage   95.59%   95.59%           
=======================================
  Files         361      361           
  Lines       11595    11602    +7     
  Branches     2683     2686    +3     
=======================================
+ Hits        11084    11091    +7     
  Misses        511      511           

Files with missing lines	Coverage Δ
...xporter-base/src/transport/http-transport-utils.ts	94.91% <100.00%> (+0.68%)	⬆️

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