Context

Following PR #1989, the SqsListener::shutdown_and_join method was updated to not return a Result<()> since with DB features added, there's no need to return an error in this call anymore.

For consistency, the S3 scanner's shutdown_and_join method should be updated similarly.

References

• PR: feat(log-ingestor): Allow an SQS listener job to spawn multiple concurrent tasks to consume notifications from the same queue (resolves #1977). #1989
• Comment: feat(log-ingestor): Allow an SQS listener job to spawn multiple concurrent tasks to consume notifications from the same queue (resolves #1977). #1989 (comment)
• Requested by: @LinZhihao-723