test: Drop disabling of SELinux in check-shutdown-restart

https://bugzilla.redhat.com/show_bug.cgi?id=1278287 got fixed in Fedora
23 three years ago already. Let's make sure we test it under the default
system configuration with SELinux enabled.

test/verify/check-shutdown-restart

@@ -64,9 +64,6 @@ class TestShutdownRestart(MachineCase):
         m2 = self.machines['machine2']
         b2 = self.new_browser(m2)
 
-        # HACK -https://bugzilla.redhat.com/show_bug.cgi?id=1278287
-        m.execute("! selinuxenabled || setenforce 0")
-
         m.start_cockpit()
 
         self.login_and_go("/system")