Fix issue with ADOT auto-instrumentation and AWS Lambda Trace Id

[normj]

Fixes

Fix issue when using ADOT auto-instrumentation which includes a version of OpenTelemetry.Instrumentation.AWSLambda in the Lambda layer. In this scenario nothing is forcing the NuGet resolution to include the updated version of Amazon.Lambda.Core that has the reworked logic for determining the trace id.

This is causing us some breaking issues with ADOT and are looking to get this fix released as soon as possible.

Changes

Add defensive code around accessing the LambdaTraceProvider.CurrentTraceId and fallback to the environment variable if we get a TypeLoadException. We need to try and use LambdaTraceProvider.CurrentTraceId to support Lambda's recently released Managed Instances where there is concurrency and an environment variable will not work. For users using Managed Instances feature they are required to use the updated version of Amazon.Lambda.Core in their Lambda function.

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)

[codecov]

Codecov Report

❌ Patch coverage is 44.44444% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.39%. Comparing base (9f71a33) to head (a0b8791).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...ntation.AWSLambda/Implementation/AWSLambdaUtils.cs	37.50%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3629      +/-   ##
==========================================
- Coverage   71.41%   71.39%   -0.02%     
==========================================
  Files         443      444       +1     
  Lines       17519    17527       +8     
==========================================
+ Hits        12511    12514       +3     
- Misses       5008     5013       +5     

Flag	Coverage Δ
unittests-Instrumentation.AWS	83.42% <44.44%> (-0.39%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
....AWSLambda/Implementation/TraceProviderIsolated.cs	100.00% <100.00%> (ø)
...ntation.AWSLambda/Implementation/AWSLambdaUtils.cs	78.72% <37.50%> (-4.04%)	⬇️

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[normj]

@martincostello Addressed your comments