Fix handling of systemd.

Systemd enablement has to happen on the server side, since we need
check if the image is running systemd.

Also need to make sure user setting the StopSignal is not overriden on the
server side. But if not set and using systemd, we set it correctly.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

test/e2e/systemd_test.go

@@ -8,7 +8,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/containers/libpod/pkg/cgroups"
 	. "github.com/containers/libpod/test/utils"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -82,13 +81,6 @@ WantedBy=multi-user.target
 	})
 
 	It("podman run container with systemd PID1", func() {
-		cgroupsv2, err := cgroups.IsCgroup2UnifiedMode()
-		Expect(err).To(BeNil())
-		if cgroupsv2 {
-			// TODO: Find a way to enable this for v2
-			Skip("systemd test does not work in cgroups V2 mode yet")
-		}
-
 		systemdImage := "fedora"
 		pull := podmanTest.Podman([]string{"pull", systemdImage})
 		pull.WaitWithDefaultTimeout()