[flakiness] Fix regex comparison which causes client_lb test to flake at a high rate internally when event engine is enabled. (#34607)

test/cpp/end2end/client_lb_end2end_test.cc

@@ -615,6 +615,8 @@ class ClientLbEnd2endTest : public ::testing::Test {
                         "(ipv6:%5B::1%5D|ipv4:127.0.0.1):[0-9]+: "
                         "(Failed to connect to remote host: )?"
                         "(Connection refused|Connection reset by peer|"
+                        "recvmsg:Connection reset by peer|"
+                        "getsockopt\\(SO\\_ERROR\\): Connection reset by peer|"
                         "Socket closed|FD shutdown)");
   }