Remove dependency on /etc/sysconfig/network-scripts

[jfut]

/etc/sysconfig/network-scripts has been removed in RHEL9.

# nmcli-cli-slave-list br1
grep: /etc/sysconfig/network-scripts/ifcfg-*: No such file or directory
grep: /etc/sysconfig/network-scripts/ifcfg-*: No such file or directory

list:

# grep network-scripts nmcli-cli-*
nmcli-cli-autoconnect-list:    grep "^ONBOOT=${ON_OFF}" /etc/sysconfig/network-scripts/ifcfg-* | cut -d':' -f 1 | sed 's|.*/ifcfg-||g'
nmcli-cli-bond-delete:    SLAVE_LIST=$(grep "^MASTER=${BOND_IF_NAME}$" /etc/sysconfig/network-scripts/ifcfg-* | cut -d':' -f 1 | egrep -o "bond-slave.*")
nmcli-cli-bridge-delete:    SLAVE_LIST=$(grep "^BRIDGE=${BRIDGE_NAME}$" /etc/sysconfig/network-scripts/ifcfg-* | cut -d':' -f 1 | sed 's|.*/ifcfg-||g')
nmcli-cli-slave-list:    SLAVE_LIST=$(grep "^MASTER=${IF_NAME}$" /etc/sysconfig/network-scripts/ifcfg-* | cut -d':' -f 1 | egrep -o "bond-slave.*")
nmcli-cli-slave-list:    SLAVE_LIST=$(grep "^BRIDGE=${IF_NAME}$" /etc/sysconfig/network-scripts/ifcfg-* | cut -d':' -f 1 | sed 's|.*/ifcfg-||g')
nmcli-cli-slave-list:    IFCFG_FILE="/etc/sysconfig/network-scripts/ifcfg-${IF_NAME}"