Use Go canonical import paths

Add canonical imports only in existing doc.go files.
https://golang.org/doc/go1.4#canonicalimports

Fixes #29014

plugin/pkg/scheduler/algorithm/doc.go

@@ -16,4 +16,4 @@ limitations under the License.
 
 // Package scheduler contains a generic Scheduler interface and several
 // implementations.
-package algorithm
+package algorithm // import "k8s.io/kubernetes/plugin/pkg/scheduler/algorithm"