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>.
update .dockercfg content to config.json
update the data format of .dockercfg to match the new docker config.json
format, which encapsulates all registry auth objects in an overall
"auths" object when an option `--config-format` is specified with the value
`--config-format=config.json`:
```
{
"auths": {
"reg.url": {
"auth": "...=="
}
}
}
```
**Release note**:
```release-note
secret data containing Docker registry auth objects is now generated using the config.json format
```
cc @bparees @fabianofranz
67e9fb6288