0e493c11c2
This commit decouples stresser from the tester of functional-tester. For doing it, this commit adds a new option --stresser to etcd-tester. The option accepts two types of stresser: "default" and "nop". If the option is "default", etcd-tester stresses its etcd cluster with the existing stresser. If the option is "nop", etcd-tester does nothing for stressing. Partially fixes https://github.com/coreos/etcd/issues/6446