Add OtlpLogExporter.Export method tests

[mfogliatto]

Fixes #2873.

Changes

• Adds the following unit tests in OtlpLogExporterTests to increase OtlpLogExporter's code coverage to ~100%:

  • Export_WhenExportClientIsProvidedInCtor_UsesProvidedExportClient
  • Export_WhenExportClientThrowsException_ReturnsExportResultFailure
  • Export_WhenExportIsSuccessful_ReturnsExportResultSuccess

For significant contributions please make sure you have completed the following items:

• Appropriate CHANGELOG.md updated for non-trivial changes N/A
• Design discussion issue N/A
• Changes in public API reviewed N/A

References

Codecov: https://app.codecov.io/gh/open-telemetry/opentelemetry-dotnet/blob/main/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpLogExporter.cs

[linux-foundation-easycla]

• ❌ The commit (1d27429). This user is missing the User's ID, preventing the EasyCLA check. Consult GitHub Help to resolve.For further assistance with EasyCLA, please submit a support request ticket.

[cijothomas]

@mfogliatto We'll need you to sign the CLA part. The Bot message should have all the instructions. You may want to consult your company policies if you are contributing as part of a company.

[github-actions]

This PR was marked stale due to lack of activity and will be closed in 7 days. Commenting or Pushing will instruct the bot to automatically remove the label. This bot runs once per day.

[cijothomas]

/easycla

[codecov]

Codecov Report

Merging #4236 (5ce3339) into main (7139c7a) will decrease coverage by 1.22%.
The diff coverage is 58.17%.

❗ Current head 5ce3339 differs from pull request most recent head 1d27429. Consider uploading reports for the commit 1d27429 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4236      +/-   ##
==========================================
- Coverage   85.57%   84.36%   -1.22%     
==========================================
  Files         291      296       +5     
  Lines       11398    11791     +393     
==========================================
+ Hits         9754     9947     +193     
- Misses       1644     1844     +200     

Impacted Files	Coverage Δ
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	81.25% <ø> (-1.11%)	⬇️
...elemetry.Exporter.Console/ConsoleMetricExporter.cs	0.00% <0.00%> (ø)
...ensions.Hosting/OpenTelemetryServicesExtensions.cs	100.00% <ø> (+60.00%)	⬆️
...emetry/Metrics/Exemplar/AlwaysOffExemplarFilter.cs	0.00% <0.00%> (ø)
...metry/Metrics/Exemplar/TraceBasedExemplarFilter.cs	0.00% <0.00%> (ø)
...tryProtocol/Implementation/MetricItemExtensions.cs	83.11% <10.00%> (-10.85%)	⬇️
.../OpenTelemetry/Logs/OpenTelemetryLoggerProvider.cs	90.90% <50.00%> (-0.85%)	⬇️
...lemetry/Metrics/Exemplar/AlwaysOnExemplarFilter.cs	50.00% <50.00%> (ø)
src/OpenTelemetry/ProviderExtensions.cs	95.00% <50.00%> (-5.00%)	⬇️
src/OpenTelemetry/Metrics/MetricPoint.cs	56.84% <54.29%> (-17.31%)	⬇️
... and 19 more

... and 7 files with indirect coverage changes

[mfogliatto]

Close PR and re-raised a separate one, as EasyCLA kept failing even after signing the agreement.