Revert "Coerce connectivity "LIMITED" to "NONE" when device is disconnected"

NMConnectivity can now distinguish between LIMITED and NONE connectivity
and it does so based on whether IP addresses and routes are configured.

Previously, NMConnectivity would not differenciate between limited and
no connectivity, which is why NMDevice added some additional logic on top
to coerce LIMITED to NONE (if the device is not logically connected).

But note that the connectivity state (whether a network is reachable on
an interface) depends on what is configured in kernel and whether the
internet is reachable on that interface. It does not depend on the
logical device state.

On the other hand, whether the device is configured in a manner to have
connectivity depends on the logical state of the device (as NetworkManager
is configuring the device).

So, in many cases, the logical state and the connectivity state agree now,
but for the right reasons.

This reverts commit 4c4dbcb7.
15 jobs for bg/concheck-issue181 in 42 minutes and 46 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Test
passed #366030
allowed to fail
checkpatch

00:01:11

manual #366035
allowed to fail manual
t_centos:7.5.1804
passed #366036
t_centos:7.6.1810

00:25:06

passed #366039
t_debian:9

00:18:46

passed #366041
t_debian:sid

00:18:45

manual #366040
allowed to fail manual
t_debian:testing
passed #366031
t_fedora:28

00:26:44

passed #366032
t_fedora:29

00:28:50

passed #366033
t_fedora:30

00:24:15

manual #366034
allowed to fail manual
t_fedora:rawhide
passed #366037
t_ubuntu:16.04

00:19:00

passed #366866
t_ubuntu:18.04

00:12:38

failed #366038
t_ubuntu:18.04

00:13:44

 
  External
passed NetworkManager test verification

passed NetworkManager test verification

05:43:09