vpn: set STOPPED state when service disappears

When the VPN service daemon fails it sends a state-change signal to NM
and quits; however it is difficult to guarantee that the signal is
delivered to NM before the process termination and so in some cases
the signal is lost. Work around that by manually setting the STOPPED
state when the service disappears from the bus.
12 jobs for bg/vpn-persistent-rh1706375 in 27 minutes and 31 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test
passed #290205
allowed to fail
checkpatch

00:01:24

passed #290212
t_debian:9

00:14:28

passed #290214
t_debian:sid

00:13:09

manual #290213
allowed to fail manual
t_debian:testing
passed #290206
t_fedora:28

00:23:38

passed #290207
t_fedora:29

00:27:30

passed #290208
t_fedora:30

00:23:49

manual #290209
allowed to fail manual
t_fedora:rawhide
passed #290210
t_ubuntu:16.04

00:09:46

passed #290211
t_ubuntu:18.04

00:13:13

 
  External
passed NetworkManager test verification

passed NetworkManager test verification

06:04:21