Add e2e test coverage for kmesh manage

[hzxuzhonghu]

We can enroll/unenroll a pod to kmesh at any time: before pod start or after it starts

And even by two methods: 1. label pod 2. label namespace

UT can only test part of that, because in reality both kmesh cni and manage controller works at different phase

[hzxuzhonghu]

@YaoZengzeng

[YaoZengzeng]

/assign