Adjust retransmission credit after PING gets sent in QuicSentPacketManagerTest.ClearLastInflightPacketsSentTime.

PiperOrigin-RevId: 313652894
Change-Id: I23e9cf3e09b354fe459bc58265356fa90094c664
diff --git a/quic/core/quic_sent_packet_manager_test.cc b/quic/core/quic_sent_packet_manager_test.cc
index 8cfbafa..c81e960 100644
--- a/quic/core/quic_sent_packet_manager_test.cc
+++ b/quic/core/quic_sent_packet_manager_test.cc
@@ -3977,6 +3977,7 @@
     manager_.MaybeSendProbePackets();
     // PING packet gets sent.
     SendPingPacket(6, ENCRYPTION_INITIAL);
+    manager_.AdjustPendingTimerTransmissions();
 
     // Verify PTO is armed based on packet 2.
     EXPECT_EQ(packet2_sent_time + pto_delay * 2,