Fix memory check script so it works in Debian Bullseye

3 jobs for upgrade-monitoring-to-bullseye in 14 minutes and 28 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Check Code
passed check-code #222674
docker

00:01:24

 
  Tests
passed compile-profiles #222675
docker

00:13:03

passed enc-test #222676

00:00:42