Automated g4 rollback of changelist 314796960.

*** Reason for rollback ***

Break GFE QUIC loadtesting.

*** Original change description ***

Wait for pending ACKs to be flushed in QuicTestClient::WaitUntil and  QuicTestClient::WaitForWriteToFlush to avoid server's unnecessary retransmission in tests.

***

PiperOrigin-RevId: 314934718
Change-Id: Ia06d9a82c25631e29146b041d579ee4ac3dc9a3a

quic/test_tools/quic_test_client.cc

diff --git a/quic/test_tools/quic_test_client.cc b/quic/test_tools/quic_test_client.cc
index df54c21..9c1c4f3 100644
--- a/quic/test_tools/quic_test_client.cc
+++ b/quic/test_tools/quic_test_client.cc
@@ -661,9 +661,7 @@
           ->GetClock();
   QuicTime end_waiting_time =
       clock->Now() + QuicTime::Delta::FromMicroseconds(timeout_us);
-  while ((HaveActiveStream() ||
-          client()->session()->connection()->HasPendingAcks()) &&
-         !(trigger && trigger()) &&
+  while (HaveActiveStream() && !(trigger && trigger()) &&
          (timeout_us < 0 || clock->Now() < end_waiting_time)) {
     client_->WaitForEvents();
   }
@@ -847,8 +845,7 @@
 }
 
 void QuicTestClient::WaitForWriteToFlush() {
-  while (connected() && (client()->session()->HasDataToWrite() ||
-                         client()->session()->connection()->HasPendingAcks())) {
+  while (connected() && client()->session()->HasDataToWrite()) {
     client_->WaitForEvents();
   }
 }