Automatic merge from submit-queue (batch tested with PRs 46425, 47975)

make proto time precision match json

json readers/writers see second precision, but protobuf readers/writers seen nanosecond precision.  This means that a json client can read and write and accidentally mutate fields as seen by protobuf clients.

This makes the precision consistent.

@kubernetes/sig-api-machinery-misc @smarterclayton 

```release-note
Update protobuf time serialization for a one second granularity
```