Fix Golang: lambda-function-sqs-report-batch-item-failures

[julianwood]

Description of changes: The Golang example for SQS processing has a placeholder for message processing. Without manually amending the code, this causes the build process to fail as there's no actual condition. Suggested fix is adding a log line, similar to other examples which prints the message body to show success. The other issue is all records would go to the batchItemFailures so adding an else statement. Also removed encoding/json as not used.

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