[8.15](backport #41071) Missing backup and delete for AWS S3 polling …

…mode (#41122)

* Missing backup and delete for AWS S3 polling mode (#41071)

(cherry picked from commit f47cbd6)


---------

Co-authored-by: kaiyan-sheng <kaiyan.sheng@elastic.co>

CHANGELOG.next.asciidoc

@@ -97,6 +97,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Prevent GCP Pub/Sub input blockage by increasing default value of `max_outstanding_messages` {issue}35029[35029] {pull}38985[38985]
 - Updated Websocket input title to align with existing inputs {pull}39006[39006]
 - Fix replace processor handling of zero string replacement validation. {pull}40751[40751]
+- Add backup and delete for AWS S3 polling mode feature back. {pull}41071[41071]
 
 *Heartbeat*
 

x-pack/filebeat/input/awss3/s3_input.go

@@ -172,6 +172,10 @@ func (in *s3PollerInput) workerLoop(ctx context.Context, workChan <-chan *s3Fetc
 
 		// Metrics
 		in.metrics.s3ObjectsAckedTotal.Inc()
+
+		if finalizeErr := objHandler.FinalizeS3Object(); finalizeErr != nil {
+			in.log.Errorf("failed finalizing objects from S3 bucket (manual cleanup is required): %w", finalizeErr)
+		}
 	}
 }