[cfgmgr/natmgrd] added disabling of NAT feature (Azure#1835)

[KonstiantynHalushka]

Signed-off-by: KonstiantynHalushka [email protected]

What I did Added disabling of NAT feature Why I did it IP table rule was not removed after config reload (Azure#1835) How I verified it sudo config feature state nat enabled sudo config nat feature enable sudo iptables -nL -t nat

target prot opt source destination DNAT all -- 0.0.0.0/0 0.0.0.0/0 to:1.1.1.1 fullcone Chain INPUT (policy ACCEPT) target prot opt source destination Chain POSTROUTING (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination

sudo config reload sudo iptables -nL -t nat

Chain PREROUTING (policy ACCEPT) target prot opt source destination
Chain INPUT (policy ACCEPT) target prot opt source destination
Chain POSTROUTING (policy ACCEPT) target prot opt source destination
Chain OUTPUT (policy ACCEPT) target prot opt source destination

Details if related

[KonstiantynHalushka]

/azpw run

[mssonicbld]

/AzurePipelines run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[KonstiantynHalushka]

@prsunny please, review this PR

[AkhileshSamineni]

@KonstiantynHalushka Please address my comment.

[KonstiantynHalushka]

@AkhileshSamineni Could you tell me exactly what you mean?