fix vpc, vsw and sg bug

[xiaozhu36]

add retry while creating vpc and vswitch result from vpc and vsw don't solve concurrent bug;
delete system created security group while delete vpc;
change security_groups's attribution optional to required when creating ecs instance.

[CLAassistant]

Thank you for your submission, we really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

heguimin seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}