Fix xds_end2end_test msan flake

test/cpp/end2end/xds_end2end_test.cc

@@ -5444,17 +5444,17 @@ class XdsSecurityTest : public BasicTest {
     }
     balancers_[0]->ads_service()->SetCdsResource(cluster);
     // The updates might take time to have an effect, so use a retry loop.
-    constexpr int kRetryCount = 10;
+    constexpr int kRetryCount = 100;
     int num_tries = 0;
     for (; num_tries < kRetryCount; num_tries++) {
       // Give some time for the updates to propagate.
       gpr_sleep_until(grpc_timeout_milliseconds_to_deadline(100));
-      ShutdownBackend(0);
-      StartBackend(0);
-      ResetBackendCounters();
       if (test_expects_failure) {
-        Status status = SendRpc();
-        if (status.ok()) {
+        // Restart the servers to force a reconnection so that previously
+        // connected subchannels are not used for the RPC.
+        ShutdownBackend(0);
+        StartBackend(0);
+        if (SendRpc().ok()) {
           gpr_log(GPR_ERROR, "RPC succeeded. Failure expected. Trying again.");
           continue;
         }