[receiver/otlp] Refactor http error handling

[TylerHelmuth]

Description:
This PR slightly refactors the otlp receiver's HTTP error handling. The result is a few less calls to status.FromError, increased accuracy in the grpc code included in the body of the response, and centralizing http<->grpc mapping in the internal/errors package.

This PR intentionally changes how we map from HTTP status code to grpc Status.code. I don't consider this to be a breaking change, or even worthy of a changelog, since the specification states that "The clients are not expected to alter their behavior based on Status.code field but MAY record it for troubleshooting purposes." Honestly, I'd be ok if we chose to stop including the Status.code entirely as it leads to more confusion in the code and payload in my opinion.

Link to tracking Issue:
Closes #9864

Testing:
Added new tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.34%. Comparing base (2ff9795) to head (ff62207).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9893      +/-   ##
==========================================
+ Coverage   91.32%   91.34%   +0.01%     
==========================================
  Files         357      357              
  Lines       19179    19196      +17     
==========================================
+ Hits        17516    17534      +18     
+ Misses       1335     1334       -1     
  Partials      328      328              

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