There were several sshPort values in e2e test packages because
we've migrated code from e2e framework by copying and pastting.
This adds common SSHPort on e2essh package to reduce such duplicated
code.
RestartControllerManager() is kube-controller specific function
and it is better to separate the function as subpackage of e2e
test framework.
In addition, the function made invalid dependency into e2essh.
So this separates the function into e2ekubesystem subpackage.
