test: Fix race condition in test setup

Stop podman.service before setting up the /var/lib/containers/ overlay
directory, so that we don't clobber an already existing /overlay mount
inside it.

Also, stop podman.service before tearing down the temporary
/var/lib/containers/.

Don't enable podman.socket in vm.install, as the tests already do it,
and talking to podman before the restore_dir() would mess things up.

test/check-application

@@ -38,14 +38,16 @@ class TestApplication(testlib.MachineCase):
 
     def setUp(self):
         super().setUp()
+        self.machine.execute("systemctl stop podman.service; systemctl --now enable podman.socket")
+
         # backup/restore pristine podman state, so that tests can run on existing testbeds
         self.restore_dir("/var/lib/containers")
+        self.addCleanup(self.machine.execute, "systemctl stop podman.service")
+
         # HACK: sometimes podman leaks mounts
         self.addCleanup(self.machine.execute, "podman rm --force --all && "
             "findmnt --list -otarget | grep /var/lib/containers/. | xargs -r umount || true")
 
-        self.machine.execute("systemctl stop podman.service; systemctl --now enable podman.socket")
-
         # Create admin session
         self.machine.execute("""
             mkdir /home/admin/.ssh

test/vm.install

@@ -42,7 +42,7 @@ if [ -d /var/tmp/debian ]; then
     systemctl disable docker.service io.podman.service
 fi
 
-systemctl enable cockpit.socket podman.socket
+systemctl enable cockpit.socket
 
 # don't force https:// (self-signed cert)
 printf "[WebService]\\nAllowUnencrypted=true\\n" > /etc/cockpit/cockpit.conf