Revert "unit: make udev rules really take precedence over tmpfiles"

Revert "unit: make udev rules really take precedence over tmpfiles"

This reverts commits 112a41b6ece19d03e951d886fe2f26512ab31fab,
3178698bb5352989e4bff866641838b1c2a0efcb, and
b768379e8b494b025f41946205944a6f3a1a553f.

The commit 112a41b6ece19d03e951d886fe2f26512ab31fab introduces #28765,
as systemd-tmpfiles-setup.service has ordering after local-fs.target,
but usually the target requires block devices processed by udevd.
Hence, the service can only start after the block devices timed out.

Fixes #28765.