Removes deprecated InsertPacket/TimeToSendPacket/TimeToSendPadding

The methods are no longer in use, this CL cleans away references and
updates any tests using them.

Bug: webrtc:10633
Change-Id: I2db301e0a021a2f85a8b9a74e409303baba407da
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/150520
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28956}

modules/rtp_rtcp/include/rtp_rtcp.h

@@ -282,22 +282,12 @@ class RtpRtcp : public Module, public RtcpFeedbackSenderInterface {
                                  int payload_type,
                                  bool force_sender_report) = 0;
 
-  virtual RtpPacketSendResult TimeToSendPacket(
-      uint32_t ssrc,
-      uint16_t sequence_number,
-      int64_t capture_time_ms,
-      bool retransmission,
-      const PacedPacketInfo& pacing_info) = 0;
-
   // Try to send the provided packet. Returns true iff packet matches any of
   // the SSRCs for this module (media/rtx/fec etc) and was forwarded to the
   // transport.
   virtual bool TrySendPacket(RtpPacketToSend* packet,
                              const PacedPacketInfo& pacing_info) = 0;
 
-  virtual size_t TimeToSendPadding(size_t bytes,
-                                   const PacedPacketInfo& pacing_info) = 0;
-
   virtual std::vector<std::unique_ptr<RtpPacketToSend>> GeneratePadding(
       size_t target_size_bytes) = 0;