fix: improve some log messages (#1747)

## Description:
Addresses Kevin's slack comment
[here](https://kurtosistech.slack.com/archives/C032ZB39AHH/p1699371636437979)

## Is this change user facing?
YES

container-engine-lib/lib/backend_impls/docker/docker_kurtosis_backend/logs_aggregator_functions/create_logs_aggregator.go

@@ -31,7 +31,7 @@ func CreateLogsAggregator(
 		return nil, nil, stacktrace.Propagate(err, "An error occurred getting logs aggregator container.")
 	}
 	if found {
-		logrus.Warnf("Found existing logs aggregator; cannot start a new one.")
+		logrus.Debugf("Found existing logs aggregator; cannot start a new one.")
 		logsAggregatorObj, _, err := getLogsAggregatorObjectAndContainerId(ctx, dockerManager)
 		if err != nil {
 			return nil, nil, stacktrace.Propagate(err, "An error occurred getting existing logs aggregator.")

container-engine-lib/lib/backend_impls/docker/docker_manager/docker_manager.go

@@ -1250,7 +1250,7 @@ func (manager *DockerManager) FetchLatestImage(ctx context.Context, dockerImage
 func (manager *DockerManager) FetchImage(ctx context.Context, image string, downloadMode image_download_mode.ImageDownloadMode) (bool, string, error) {
 	var err error
 	var pulledFromRemote bool = true
-	logrus.Infof("Fetching image '%s' is running in '%s' mode", image, downloadMode)
+	logrus.Debugf("Fetching image '%s' with image download mode: %s", image, downloadMode)
 
 	switch image_fetching := downloadMode; image_fetching {
 	case image_download_mode.ImageDownloadMode_Always: