When a process is stopped:
- it may not have emitted logs since previous rotation: add "missingok"
  As a direct consequence: stop using logrotate recipe.
- its pid file (if applicable) may be missing: test its non-empty presence
  before calling slapos-kill
Also, stop using slapos.cookbook:logrotate.
Update obvious users (cloudooo, neoppod, erp5, monitor, re6stnet).