Simplify the usage of ack_frequency and ack_delay in quic_received_packet_manager. flag protected by gfe2_reloadable_flag_quic_simplify_received_packet_manager_ack.

A few other no-op changes:
1) Renamed ack_frequency_before_decimation to ack_frequency_.
2) Removed a few unused getters in uber_received_packet_manager and quic_connection.

PiperOrigin-RevId: 323473745
Change-Id: I51f119d048271543b5a7ae000d3d4bcffc3679ab
diff --git a/quic/core/uber_received_packet_manager.h b/quic/core/uber_received_packet_manager.h
index d76ce13..9cfa247 100644
--- a/quic/core/uber_received_packet_manager.h
+++ b/quic/core/uber_received_packet_manager.h
@@ -78,8 +78,7 @@
   size_t min_received_before_ack_decimation() const;
   void set_min_received_before_ack_decimation(size_t new_value);
 
-  size_t ack_frequency_before_ack_decimation() const;
-  void set_ack_frequency_before_ack_decimation(size_t new_value);
+  void set_ack_frequency(size_t new_value);
 
   bool supports_multiple_packet_number_spaces() const {
     return supports_multiple_packet_number_spaces_;
@@ -91,8 +90,7 @@
 
   void set_max_ack_ranges(size_t max_ack_ranges);
 
-  // Get and set the max ack delay to use for application data.
-  QuicTime::Delta max_ack_delay();
+  // Set the max ack delay to use for application data.
   void set_max_ack_delay(QuicTime::Delta max_ack_delay);
 
   void set_save_timestamps(bool save_timestamps);