[logtail] Flush stdout after printing logs
[logtail] Flush stdout after printing logs

This will make `logtail -r REQUEST | grep something` work as expected
hs-jenkins-bot/Singularity,hs-jenkins-bot/Singularity,andrhamm/Singularity,HubSpot/Singularity,HubSpot/Singularity,andrhamm/Singularity,andrhamm/Singularity,andrhamm/Singularity,hs-jenkins-bot/Singularity,HubSpot/Singularity,hs-jenkins-bot/Singularity,andrhamm/Singularity,HubSpot/Singularity,hs-jenkins-bot/Singularity,HubSpot/Singularity