device: keep client running after activation failure

If DHCPv4 fails but IPv6 succeeds it makes sense to continue trying
DHCP so that we will eventually be able to get an address if the DHCP
server comes back. Always keep the client running; it will be only
terminated when the connection is brought down.

https://bugzilla.redhat.com/show_bug.cgi?id=1688329
17 jobs for bg/dhcp-keep in 37 minutes and 43 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Test
passed #611620
allowed to fail
checkpatch

00:01:21

manual #611625
allowed to fail manual
t_centos:7.5.1804
passed #611626
t_centos:7.6.1810

00:26:27

passed #611632
t_debian:10

00:22:44

passed #611631
t_debian:9

00:22:23

passed #611634
t_debian:sid

00:22:34

manual #611633
allowed to fail manual
t_debian:testing
passed #611621
t_fedora:28

00:32:11

passed #611622
t_fedora:29

00:37:43

passed #611623
t_fedora:30

00:31:11

manual #611624
allowed to fail manual
t_fedora:rawhide
passed #611627
t_ubuntu:16.04

00:22:03

passed #611628
t_ubuntu:18.04

00:23:13

manual #611630
allowed to fail manual
t_ubuntu:devel
manual #611629
allowed to fail manual
t_ubuntu:rolling
 
  External
passed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/704/

passed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/704/

06:42:43