test: support testing on versions Cockpit < 329

With the release of Cockpit 329 the add host dialog now warns the user
before adding a remote host. Cockpit's testlib add host helper function
defaults to this behaviour but our test images still have an older
version of Cockpit installed.

test/check-machines-multi-host-consoles

@@ -68,7 +68,9 @@ class TestMultiMachineVNC(VirtualMachinesCase):
         self.goToVmPage(name)
         b.wait_in_text(f"#vm-{name}-system-state", "Running")
 
-        b.add_machine(m2_host, known_host=True, password=None)
+        # Cockpit 329 warns the user before adding a remote host
+        cockpit_version = m.execute("cockpit-bridge --version | head -n 1 | awk '{ print $2 }'").strip()
+        b.add_machine(m2_host, known_host=True, password=None, expect_warning=cockpit_version > "328")
 
         b.switch_to_top()
         b.click("#hosts-sel button")