systemd: set no default dependencies

https://github.com/systemd/systemd/issues/23763

cloning to here:

We have a critical networking related early boot service that uses dbus and have a dependency placed on dbus.socket, During performance analysis, we noticed that our service is starting late due to default dependencies like sysinit.target injected into our service via dbus.socket. Therefore, we are missing our requirements.

before:
-dbus.socket @3.417s
-sysinit.target @3.415s
-cryptsetup.target @3.414s
-systemd-ask-password-wall.path @358ms
--.mount @339ms--.slice @339ms

We are able to resolve this issue if we inject DefaultDependencies=No into dbus.socket similar to all other socket entries started during boot.

after:
`-sys-devices-platform-xyz @742ms

Now, we are questioning the correctness of this approach and if this is something we could contribute upstream.