Add cloud.platform attribute to resource attributes in lambda (#561)

*Description of changes:*

Same as:

aws-observability/aws-otel-js-instrumentation#308

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Author: liustve

lambda-layer/src/otel-instrument

@@ -92,7 +92,7 @@ if [ -z "${OTEL_SERVICE_NAME}" ]; then
 fi
 
 
-export LAMBDA_RESOURCE_ATTRIBUTES="cloud.region=$AWS_REGION,cloud.provider=aws,faas.name=$AWS_LAMBDA_FUNCTION_NAME,faas.version=$AWS_LAMBDA_FUNCTION_VERSION,faas.instance=$AWS_LAMBDA_LOG_STREAM_NAME,aws.log.group.names=$AWS_LAMBDA_LOG_GROUP_NAME";
+export LAMBDA_RESOURCE_ATTRIBUTES="cloud.region=$AWS_REGION,cloud.platform=aws_lambda,cloud.provider=aws,faas.name=$AWS_LAMBDA_FUNCTION_NAME,faas.version=$AWS_LAMBDA_FUNCTION_VERSION,faas.instance=$AWS_LAMBDA_LOG_STREAM_NAME,aws.log.group.names=$AWS_LAMBDA_LOG_GROUP_NAME";
 
 if [ -z ${OTEL_PROPAGATORS} ]; then
     export OTEL_PROPAGATORS="baggage,xray,tracecontext"