This mimics what we do for systemd-cryptsetup@.service (see
src/shared/generator.c), and makes sense since repart might lock up the
root volume against a TPM, which ideally has its SRK already set up by
then.
More importantly though, this ensures that we ordered correctly after
tpm2.target (which systemd-tpm2-setup-early.service has a dependency
on), for systems where the TPM drivers are not compiled into the kernel.
See: https://lists.freedesktop.org/archives/systemd-devel/2024-April/050201.html
