feat: OTLP Exporter builders to return specific Error type

[cijothomas]

Fixes #2561

Also removes now unused Error enum from Log SDK. Another set of cleanup required to clean Metrics, Traces completely.
Also, the newly introduced enum ExporterBuildError is not fully refined, this can be done in follow ups. This is necessary to unblock Log SDK Stable Release.

Note: This is a breaking change for OTLP Exporter, however, the impact is minimal (most users/examples simply unwrap/expect the Result instead of matching on it.), as described in the changelog, so I propose to make the change even though OTLP Exporter is marked RC.

[codecov]

Codecov Report

Attention: Patch coverage is 73.61111% with 19 lines in your changes missing coverage. Please review.

Project coverage is 80.1%. Comparing base (8aa5b00) to head (3171749).

Files with missing lines	Patch %	Lines
opentelemetry-otlp/src/exporter/http/mod.rs	68.0%	8 Missing ⚠️
opentelemetry-otlp/src/exporter/mod.rs	90.3%	3 Missing ⚠️
opentelemetry-otlp/src/exporter/tonic/mod.rs	66.6%	3 Missing ⚠️
opentelemetry-otlp/src/metric.rs	0.0%	2 Missing ⚠️
opentelemetry-otlp/src/span.rs	0.0%	2 Missing ⚠️
opentelemetry-otlp/src/exporter/http/logs.rs	0.0%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #2790     +/-   ##
=======================================
+ Coverage   79.6%   80.1%   +0.5%     
=======================================
  Files        124     123      -1     
  Lines      23174   23191     +17     
=======================================
+ Hits       18456   18591    +135     
+ Misses      4718    4600    -118     

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Pull Request Overview

This PR refactors the OTLP Exporter builders to return a well-defined error type (ExporterBuildError) instead of a generic or signal‐specific error, thereby improving error handling clarity and consistency. It also removes an unused Error enum from the Log SDK and updates tests, examples, and changelogs to reflect these breaking changes.

• Update error type definitions and conversions across tonic and http exporters.
• Remove the unused Log SDK error enum.
• Adjust tests, examples, and changelogs to document the breaking changes.

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
opentelemetry-otlp/src/exporter/tonic/mod.rs	Updated error conversions and function signatures to use ExporterBuildError.
opentelemetry-otlp/src/exporter/mod.rs	Updated error handling in trait implementations and FromStr.
opentelemetry-otlp/src/exporter/http/mod.rs	Switched error type to ExporterBuildError and added a TODO for thread-spawn handling.
opentelemetry-sdk/CHANGELOG.md & opentelemetry-otlp/CHANGELOG.md	Documented breaking changes for the new error handling approach.
Various exporter and span modules, examples, and tests	Modified build functions and tests to accommodate the updated error type.

Comments suppressed due to low confidence (1)

opentelemetry-otlp/src/exporter/http/mod.rs:171

• Consider handling errors from thread spawning instead of using unwrap, to prevent potential panics. Propagate a proper ExporterBuildError instead of unwrapping the thread result.

.join().unwrap(), // TODO: Return ExporterBuildError::ThreadSpawnFailed