[otlp] Use LogRecord.Logger.Name for instrumentation scope if LogRecord.CategoryName is null

[AB027PS]

Fixes #5274

Changes

I made a change to OtlpLogRecordTransformer to address a situation where LogRecord.CategoryName is null
according to a suggestion in #5274

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[CodeBlanch]

@AB027PS This is good thanks! There are a few things we need to do before we can merge:

• Resolve warnings. Looks like some style issues. If you are using VS switch to Release config and rebuild that should surface everything for you locally.

• Update CHANGELOG. Add a note at the bottom of the unreleased section here:

  opentelemetry-dotnet/src/OpenTelemetry.Exporter.OpenTelemetryProtocol/CHANGELOG.md

  Line 23 in 8b54074

  Something like this...

  * Updated `OtlpLogExporter` to set instrumentation scope name on the data model
    from `LogRecord.Logger.Name` if `LogRecord.CategoryName` is `null`. This is
    typically the case when using the experimental Logs Bridge API.
    ([#5300](https://github.com/open-telemetry/opentelemetry-dotnet/pull/5300))
  

• We need a unit test. In here:

  opentelemetry-dotnet/test/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests/OtlpLogExporterTests.cs

  Line 648 in 8b54074

  Drop a test like...

   [Fact]
   public void LogRecordLoggerNameIsExportedWhenUsingBridgeApi()
   {
       LogRecordAttributeList attributes = default;
       attributes.Add("name", "tomato");
       attributes.Add("price", 2.99);
       attributes.Add("{OriginalFormat}", "Hello from {name} {price}.");
  
       var logRecords = new List<LogRecord>();
  
       using (var loggerProvider = Sdk.CreateLoggerProviderBuilder()
           .AddInMemoryExporter(logRecords)
           .Build())
       {
           var logger = loggerProvider.GetLogger("my_instrumentation_scope_name");
  
           logger.EmitLog(new LogRecordData(), attributes);
       }
  
       Assert.Single(logRecords);
  
       var otlpLogRecordTransformer = new OtlpLogRecordTransformer(DefaultSdkLimitOptions, new());
  
       var batch = new Batch<LogRecord>(new[] { logRecords[0] }, 1);
  
       var request = otlpLogRecordTransformer.BuildExportRequest(
           new Proto.Resource.V1.Resource(),
           batch);
  
       Assert.NotNull(request);
       Assert.Single(request.ResourceLogs);
       Assert.Single(request.ResourceLogs[0].ScopeLogs);
  
       Assert.Equal("my_instrumentation_scope_name", request.ResourceLogs[0].ScopeLogs[0].Scope?.Name);
   }

If you need help with anything let me know, happy to assist.

[CodeBlanch]

LGTM