test: do not bring up the network interface if it is not needed

test: do not bring up the network interface if it is not needed

Notice that TEST-04 does not explicitelly includes dhclient
and dhclient-script for the rootfs.

Apply the same principle for all local tests that do not
need networking.

This should make the tests run faster and slightly more reliable.

This change also brings us to a better place where network-legacy
files are only gets included via proper dracut module inclusion.