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>.
Remove unused variables and constant from pkg/apis/componentconfig/v1…
…alpha1/defaults.go
This commit will remove variables `zeroDuration`, `defaultNodeAllocatableEnforcement` and
constants `defaultIPTablesMasqueradeBit` and `defaultIPTablesDropBit` as they are unused.
```release-note
NONE
```