Fix OSS QUICHE build.

Mark quic_client and quic_toy_client as testonly so they can consume their new
testonly dependency.

PiperOrigin-RevId: 981960840

quiche/BUILD.bazel

diff --git a/quiche/BUILD.bazel b/quiche/BUILD.bazel
index 6b13f58..3559366 100644
--- a/quiche/BUILD.bazel
+++ b/quiche/BUILD.bazel
@@ -263,6 +263,7 @@
 
 cc_library(
     name = "quic_toy_client",
+    testonly = 1,
     srcs = [
         "quic/tools/quic_toy_client.cc",
     ],
@@ -272,6 +273,7 @@
     deps = [
         ":io_tool_support",
         ":quiche_core",
+        ":quiche_test_support",
         ":quiche_tool_support",
         "@boringssl//:crypto",
         "@com_google_absl//absl/status",
@@ -624,6 +626,7 @@
 
 cc_binary(
     name = "quic_client",
+    testonly = 1,
     srcs = ["quic/tools/quic_client_bin.cc"],
     deps = [
         ":io_tool_support",