fix "Feature computer remove unused software"

See merge request nexedi/slapos.core!293

master/bt5/slapos_pdm/SkinTemplateItem/portal_skins/slapos_pdm/SoftwareInstallation_destroyWithSoftwareReleaseArchived.py

@@ -19,6 +19,9 @@ if computer is None:
   return
 if computer.Computer_getSoftwareReleaseUsage(url_string) != 0:
   return
+if computer.getAllocationScope() not in ['open/public', 'open/subscription', 'close/forever']:
+  # handle only some specific computers: public ones and removed
+  return
 
 software_installation.requestDestroy(
   comment='Destroyed by %s as %s is archived.' % (script.id, software_release.getRelativeUrl(),))