Fix a memory leak in InitializeAndCheckForTlsPskFailure test helper

If we switch EXPECT_QUIC_BUG to use EXPECT_DCHECK_DEATH in the Chromium implementation, `client_writer_` gets leaked:

https://ci.chromium.org/ui/p/chromium/builders/try/linux_chromium_asan_rel_ng/2009331/overview

My mind is not completely made up about whether we should actually switch EXPECT_QUIC_BUG to use EXPECT_DCHECK_DEATH, but at least this change makes it so that we could.

PiperOrigin-RevId: 651757108

quiche/quic/core/http/end_to_end_test.cc

diff --git a/quiche/quic/core/http/end_to_end_test.cc b/quiche/quic/core/http/end_to_end_test.cc
index 4e46693..b7dd0ec 100644
--- a/quiche/quic/core/http/end_to_end_test.cc
+++ b/quiche/quic/core/http/end_to_end_test.cc
@@ -935,10 +935,17 @@
     // successfully.
     pre_shared_key_client_ = "";
     pre_shared_key_server_ = "";
+
     StopServer();
     server_writer_ = new PacketDroppingTestWriter();
     StartServer();
-    client_writer_ = new PacketDroppingTestWriter();
+
+    if (client_) {
+      // If `client_` is populated it means that the `CreateClientWithWriter()`
+      // call above ran in-process, in which case `client_` owns
+      // `client_writer_` and we need to create a new one.
+      client_writer_ = new PacketDroppingTestWriter();
+    }
     CreateClientWithWriter();
   }