lint: Fix deprecated import github.com/golang/protobuf/jsonpb

The dependency github.com/golang/protobuf is deprecated and should be replaced with google.golang.org/protobuf. This change replaces usage of the jsonpb package with encoding/protojson. The packages have incompatible API that is why the code changes were done to migrate. The exclusion rule removed from the golanci-lint tool configuration file to prevent future use of the deprecated package.