Improve examples test (#9467)

This PR moves the examples test to where it belongs and also include the
following improvements:

- Removed test cases defined for non-existent files;
- Add guard against ineffective tests against missing files;
- Remove the special case for scheduler-policy-config which is no longer
  an example, the dependency on the related go module is thus
  eliminated;
- Updated the .tavis.yml file to use the new test case: the instruction
  sequence is adjusted to ensure the correct version of kubernetes is
  fully prepared before we do `go get -v -t`.
- The examples_test.go is formatted using `gofmt`;
- Verbose output during test has been added.
- A separate test case is added for CN translation.

Related: #9285

content/en/examples/README.md

@@ -0,0 +1,13 @@
+Note: These tests are importing code from kubernetes that isn't really
+meant to be used outside the repo. This causes vendoring problems. As
+a result, we have to work around those with these lines in the travis
+config:
+
+```
+- rm $GOPATH/src/k8s.io/kubernetes/vendor/k8s.io/apimachinery
+- rm $GOPATH/src/k8s.io/kubernetes/vendor/k8s.io/apiserver
+- rm $GOPATH/src/k8s.io/kubernetes/vendor/k8s.io/client-go
+- cp -r $GOPATH/src/k8s.io/kubernetes/vendor/* $GOPATH/src/
+- rm -rf $GOPATH/src/k8s.io/kubernetes/vendor/*
+- cp -r $GOPATH/src/k8s.io/kubernetes/staging/src/* $GOPATH/src/
+```