Automatic merge from submit-queue (batch tested with PRs 55247, 55324, 55261, 55147, 54052). 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>.
Restore kube-proxy's support for 0 values for conntrack settings
**What this PR does / why we need it**: re-allow 0 values for kube-proxy conntrack min, max, max per core, tcp close wait timeout, tcp established timeout.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes#50787
**Special notes for your reviewer**:
- I adjusted validation to allow for 0 values for some of the conntrack settings, as otherwise the "leave the limit as-is" logic wouldn't be allowed.
- I moved the loading of the config file from the cobra command's Validate method to Complete. This way, the config is fully resolved before validation happens. Otherwise, it just validates the default config values first, and _then_ the config is loaded.
- I think I got all the default values & nil checking correct, but please review carefully!
**Release note**:
```release-note
Restored kube-proxy's support for 0 values for conntrack min, max, max per core, tcp close wait timeout, and tcp established timeout.
```
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>.
Fix lint errors in kubeproxyconfig types.
**What this PR does / why we need it**:
Fix some outstanding lint errors reported by k8s-ci-robot in https://github.com/kubernetes/kubernetes/pull/53645/files#r149212051.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes#53645
**Special notes for your reviewer**:
/cc @cblecker @ncdc
**Release note**:
```release-note
NONE
```
When kube-proxy was refactored to use a configuration file, the ability
to use 0 for conntrack min, max, max per core, and tcp timeouts was
inadvertently broken; if you specified 0, it would instead apply the
default value from defaults.go.
This change restores the ability to use 0 to mean 0.
Signed-off-by: Andy Goldstein <andy.goldstein@gmail.com>
