fix: add default route on customer vnets and provide default route from CNS to CNI

[paulyufan2]

Reason for Change:

This PR is to fix one issue in swiftv2 Windows scenario: When a pod is created, the default route is added on infra vnet: root@swiftv2-pod-3:/# ip route default via 10.244.2.1 dev eth0 metric 1 It leads to ping a VM IP in the same VNET that cannot work.

There are two issues:: 1.CNS does not provide the default route to CNI; 2.CNI should only add the default route to secondary interface customer vnet; on Swiftv2 scenario, skipDefaultRoutes is set to true for infraNIC interface and false for a secondary interface; so if !info.skipDefaultRoutes, then add default route.

Issue Fixed:

Requirements:

• [ ] uses conventional commit messages
• [ ] includes documentation
• [ ] adds unit tests
• [ ] relevant PR labels added

Notes: