On this system, a systemd-nspawn full OS container created with
debootstrap, tpm-udev.path is triggered very frequently and eventually
hits start-limit-hit a few minutes after boot.
Even bash completion of "echo /dev" is enough to trigger it.

https://bugs.launchpad.net/ubuntu/+source/tpm2-abrmd/+bug/1997259
suggests that this was added to paper over some lxd weirdness, but then
maybe the path unit should be conditional on
"ConditionVirtualization=lxc" (or whatever is right for lxd).

Anyway, it is demonstrably broken for the general case so should not be
generally enabled with any container system.

Jul 14 23:33:51 sangiorgio systemd[1]: Started tpm-udev.service - Handle dynamically added tpm devices.
Jul 14 23:33:51 sangiorgio systemd[1]: tpm-udev.service: Deactivated successfully.
Jul 14 23:33:51 sangiorgio systemd[1]: tpm-udev.service: Start request repeated too quickly.
Jul 14 23:33:51 sangiorgio systemd[1]: tpm-udev.service: Failed with result 'start-limit-hit'.