tools: frr-reload strip interface vrf ctx line

tools: frr-reload strip interface vrf ctx line

if frr.conf file contains 'interface x vrf <name> config
it causes protocol (like ospf) neighbor session flap,
as it deletes interface base config line ('interface x') from
running config and readds with 'interface x vrf <name>'
line from frr.conf.
This deletion and readdition of lines leads to neighborship
flaps.

This issue is by product of (PR-10411 | https://github.com/FRRouting/frr/pull/10411)
(commit id: 788a036fdb)
where running config for interface config no loger displays associated
vrf line.

Ticket: #3858146
Testing:

frr.conf
interface swp1.2 vrf vrf1012
ip ospf network point-to-point

running-config:
interface swp1.2
 ip ospf network point-to-point
 exit

Before fix:
frr-reload logs:

2024-04-09 00:28:31,096  INFO: Executed "interface swp1.2  no ip ospf
network point-to-point exit"

 'interface swp1.2 vrf vrf1012\n ip ospf network
 point-to-point\nexit\n',

After fix:
frr-reload strips vrf line, thus no config change between
frr.conf and running config.

Signed-off-by: Chirag Shah <chirag@nvidia.com>