auto-install: move private1-ulsfo to module

Commit Ia656e592cd07975f8d2f9bb63899c32dd7d2bdfd moved install-server
into a separate module but it was merged without a rebase, which means
that it missed subnets/private1-ulsfo.cfg that was added in the
meantime. Move this too now.

Change-Id: Ic26262a955eb2e2c6862c28a5bb48f97ae536ee3