[Bug fixes] Lambda - duplicate lambda spans + appsignals from unsampled spans

[srprash]

Issue 1 - Duplicate lambda root spans

The instrumentation produces 2 lambda root spans upon each invocation of the function. This is a known issue in OTel: open-telemetry/opentelemetry-java-instrumentation#7808

Fix

• Otel has fixed it in this PR but the change wasn't ported to the 1.x versions. So I took the diff from the upstream commit and made it into a patch that we apply when building the ADOT Java Lambda Layer for v1.33.x.

Issue 2 - Unsampled spans do not produce Application Signals metrics

On lambda environment, we export 100% of the spans to X-Ray to ensure we are able to provide 100% Application Signals metrics. However, currently only the sampled spans show up on the "Services" page and the unsampled spans do not.

Fix

• Upon comparing the sampled vs unsampled spans, I noticed that the unsampled spans are missing the attributes like aws.local.service and aws.local.operation which are required to generate Application Signals metrics.
• The fix is to wrap the OtlpUdpSpanExporter instance for unsampled spans with the AwsMetricAttributesSpanExporter so that the exported spans have the desired attributes.

Testing

• After creating a layer with the fix, I set the OTEL_TRACES_SAMPLER to always_off. Then I invoked the function once.
• The metrics appeared on the Application Signals console.
• See the following screenshots

Description of changes:

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