Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Need to validate taint effect when removing taints.
Instead of reporting taint not found, it's better to report user
that the effect is invalid. This will help user to check errors.
So when user tries to remove a taint, two conditions will be checked:
1. Whether or not the effect is an empty string.
2. Whether or not the non-empty effect is a valid taint effect.
**Release note**:
```release-note
None
```
d1c58238da