Fix flaky test embed.TestEnableAuth which can fail due to port conflict#21508

jonathan-albrecht-ibm wants to merge 3 commits intoetcd-io:mainetcd-io/etcd:mainfrom

linux-on-ibm-z:embed-tests-url-uniquifylinux-on-ibm-z/etcd:embed-tests-url-uniquifyCopy head branch name to clipboard