libnm/client: don't reset properties when interface goes awaylr/object-removal

In case the D-Bus interfaces start dropping off (typically all off them go
one by one when the object is being deleted), don't reset all the properties.

In particular, keep most properties around, only tear down "o" and "ao",
so that the object dependencies get torn down, but we still get enough
properties around to identify what the dead object was its heyday.

One example of where this is not good is when the device-removed signal
is emmitted, the device no longer has the ifname:

  $ nmcli monitor
  <quit NetworkManager>
  (null): device removed
  (null): device removed
  ...

1 files changed, 1 insertions, 4 deletions

diff --git a/src/tests/client/test-client.py b/src/tests/client/test-client.py
index 4ee64ecb86..f018fbf34a 100755
--- a/src/tests/client/test-client.py
+++ b/src/tests/client/test-client.py
@@ -1913,11 +1913,8 @@ class TestNmcli(NmTestBase):
         nmc = start_mon()
         self.srv.shutdown()
         self.srv = None
-        nmc.expect("\(null\): device removed")
+        nmc.expect("eth0: device removed")
         nmc.expect("con-1: connection profile removed")
-        nmc.expect("Hostname set to '\(null\)'")
-        nmc.expect("Networkmanager is now in the 'unknown' state")
-        nmc.expect("Connectivity is now 'unknown'")
         nmc.expect("NetworkManager is stopped")
         end_mon(nmc)