These units are also present in the initrd, so instead of an assert,
just use a condition so they are skipped where they need to be skipped.
Fixes https://github.com/systemd/systemd/issues/26358
We want PCR 15 to be useful for binding per-system policy to. Let's
measure the machine ID into it, to ensure that every OS we can
distinguish will get a different PCR (even if the root disk encryption
key is already measured into it).
Luca Boccassi
Lennart Poettering