CI failure: `test_onroad` memory usage fails after some re-runs

[maxime-desroches]

Because of magic replacing weston, you get persistent memory increases every time you restart openpilot. Tagging as CI since it causes many failures in Jenkins right now.

Example: https://jenkins.comma.life/blue/organizations/jenkins/openpilot/detail/master/260/pipeline#step-403-log-1191