Resolve rhbz#1738578

When functions provided by /etc/rc.d/functions is used, escape
sequence is output under systemd service units and logged into
/var/log/messages as follows:

    # LANG=C systemctl cat foobar.service
    # /etc/systemd/system/foobar.service
    [Unit]
    Description=FOOBAR

    [Service]
    Type=oneshot
    ExecStart=/usr/bin/foobar.sh
    RemainAfterExit=yes

    [Install]
    WantedBy=multi-user.target
    # cat /usr/bin/foobar.sh
    #! /bin/bash

    . /etc/init.d/functions
    echo_success
    # LANG=C grep foobar.sh /var/log/messages
    Aug  7 09:29:54 localhost foobar.sh[29607]: #033[60G[#033[1;32m  OK  #033[0;39m]#015#033[60G[#033[1;31mFAILED#033[0;39m]

This is a regression issue caused by the commit f88dbd98e992 where
consoletype command was dropped.

Under systemd service units, standard input is associated with
/dev/null by default:

    # systemctl show -p StandardInput foobar.service
    StandardInput=null

  man 5 systemd.exec:

     StandardInput=
         Controls where file descriptor 0 (STDIN) of the executed
         processes is connected to. Takes one of null, tty,
         tty-force, tty-fail, data, file:path, socket or fd:name.

         If null is selected, standard input will be connected to
         /dev/null, i.e. all read attempts by the process will
         result in immediate EOF.

consoletype command interprets /dev/null as serial:

    # consoletype < /dev/null
    warning: consoletype is now deprecated, and will be removed in the near future!
    warning: use tty (1) instead! More info: 'man 1 tty'
    serial

The commit f88dbd98e992 overlooks this situation.

To fix this issue, check also "not a tty" to cover the case where
standard input is /dev/null.

Note that LANG=C is needed because the message "not a tty" varies
depending on locales.

(cherry picked from commit fdcc55839df2334d7a7567de1f02f07ee7a69561)

  ... by checking existence of /etc/sysconfig/disable-deprecation-warnings

  In case of 'network' service these warnings are displayed only once,
  to not spam unnecessarily user's journalctl if they have many NICs.

  This concept is quite outdated, and not sane to use at all.

  Other references to these files were removed, as well as irrelevant
  info in sysconfig.txt, and some dead code in init.d/functions file.

  The dependance on 'consoletype' binary has been removed.