pod: block the vsw if ip not enough

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 28.02%. Comparing base (9e7b57c) to head (75761cd). Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/vswitch/vswitch.go	80.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #680 +/- ## ========================================== + Coverage 27.92% 28.02% +0.09% ========================================== Files 78 78 Lines 8565 8565 ========================================== + Hits 2392 2400 +8 + Misses 5841 5833 -8 Partials 332 332 ``` | [Flag](https://app.codecov.io/gh/AliyunContainerService/terway/pull/680/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AliyunContainerService) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/AliyunContainerService/terway/pull/680/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AliyunContainerService) | `28.02% <80.00%> (+0.09%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AliyunContainerService#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.