etcdproxy e2e tests should run in dedicated directories.

So far all proxies were sharing the same (current) directory,
leading to tests flakes, e.g. due to certificates being overriden
in autoTLS mode.

tests/e2e/cluster_proxy_test.go

@@ -186,21 +186,23 @@ func proxyListenURL(cfg *etcdServerProcessConfig, portOffset int) string {
 func newProxyV2Proc(cfg *etcdServerProcessConfig) *proxyV2Proc {
 	listenAddr := proxyListenURL(cfg, 2)
 	name := fmt.Sprintf("testname-proxy-%p", cfg)
+	dataDir := path.Join(cfg.dataDirPath, name+".etcd")
 	args := []string{
 		"--name", name,
 		"--proxy", "on",
 		"--listen-client-urls", listenAddr,
 		"--initial-cluster", cfg.name + "=" + cfg.purl.String(),
+		"--data-dir", dataDir,
 	}
 	return &proxyV2Proc{
-		proxyProc{
+		proxyProc: proxyProc{
 			lg:       cfg.lg,
 			execPath: cfg.execPath,
 			args:     append(args, cfg.tlsArgs...),
 			ep:       listenAddr,
 			donec:    make(chan struct{}),
 		},
-		name + ".etcd",
+		dataDir: dataDir,
 	}
 }
 
@@ -242,6 +244,7 @@ func newProxyV3Proc(cfg *etcdServerProcessConfig) *proxyV3Proc {
 		"--endpoints", cfg.acurl,
 		// pass-through member RPCs
 		"--advertise-client-url", "",
+		"--data-dir", cfg.dataDirPath,
 	}
 	murl := ""
 	if cfg.murl != "" {