cmd/relaynode: drop local --acl-file in favour of central packet filter.

relaynode itself is not long for this world, deprecated in favour of
tailscale/tailscaled. But now that the control server supports central
distribution of packet filters, let's actually take advantage of it in
a final, backward compatible release of relaynode.

cmd/relaynode/default.rpm.od

@@ -10,5 +10,6 @@ rpmbase=$HOME/rpmbuild
 
 mkdir -p "$rpmbase/SOURCES/"
 cp "$dir/$pkg.tar.gz" "$rpmbase/SOURCES/"
+rm -f "$rpmbase/RPMS/$machine/$pkg-$pkgver.$machine.rpm"
 rpmbuild -bb "$dir/$pkg.spec"
 mv "$rpmbase/RPMS/$machine/$pkg-$pkgver.$machine.rpm" $3