Automatic merge from submit-queue

Add benchmark to jenkins

This PR contains the following changes:

1. Add more tests in density benchmark test;
2. Add the peak value (100%) in latency and CPU usage statistic data;
3. Move the Ginkgo focus flag from e2e_remote.go to run_e2e.go;
4. Support running benchmark in run_e2e.go. The benchmark configuration file is an extension of image configuration. Each item requires additional GCE machine type (e.g. n1-standard-1, default value will be used if empty) and test names (Ginkgo focus regex strings). A test item is regarded as benchmark if the tests field is non-empty.