Delete deprecated MediaTransport methods using VideoCodecType.

This is a followup, deleting the things marked as deprecated in
https://webrtc-review.googlesource.com/c/113180.

Bug: webrtc:9719
Change-Id: I64dc31c6918f575599fc6b0bbfa47c5b1f2f3019
Reviewed-on: https://webrtc-review.googlesource.com/c/113521
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Peter Slatala <psla@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26465}

api/DEPS

@@ -107,7 +107,6 @@ specific_include_rules = {
   "media_transport_interface\.h": [
     "+rtc_base/copy_on_write_buffer.h",  # As used by datachannelinterface.h
     "+rtc_base/network_route.h",
-    "+rtc_base/deprecation.h",
   ],
 
   "peer_connection_factory_proxy\.h": [