settings: drop deprecated NetworkManager.conf option "main.monitor-connection-files"

It's deprecated and off by default for a long time.

It is bad to automatically reload connection profiles. For example, ifcfg
files may consist of multiple files, there is no guarantee that we
pick up the connection when it's fully written.

Just don't do this anymore.

Users should use D-Bus API or `nmcli connection reload` or `nmcli
connection load $FILENAME` to reload profiles from disk.
12 jobs for <span class="ref-name">th/drop-monitor-connection-files</span> in 38 minutes and 31 seconds (queued for 33 minutes and 26 seconds)
Status Job ID Name Coverage
  Test
passed #308048
allowed to fail
checkpatch

00:01:20

passed #308055
t_debian:9

00:20:57

passed #308057
t_debian:sid

00:19:43

manual #308056
allowed to fail manual
t_debian:testing
passed #308049
t_fedora:28

00:32:55

passed #308050
t_fedora:29

00:38:26

passed #308051
t_fedora:30

00:24:02

manual #308052
allowed to fail manual
t_fedora:rawhide
passed #308053
t_ubuntu:16.04

00:19:37

passed #308054
t_ubuntu:18.04

00:20:04

 
  External
passed NetworkManager test verification

passed NetworkManager test verification

05:45:37