Reapply "chore: garbage collect now, not in 3 days (#153)" (#154)

This reverts commit 4582df6.

registry/garbage-collect.sh

@@ -1,7 +1,10 @@
 #!/bin/sh
 
+echo "Script started"
+
 while true; do
-  sleep 72h # every 3 days
   echo "Starting garbage collection..."
   registry garbage-collect /etc/docker/registry/config.yml || true
+  echo "Garbage collection finished"
+  sleep 72h # every 3 days
 done