Deprecate EventFactory and delete all usage.

Will be deleted as soon as downstream calls of
VideoCodingModule::Create are updated.

Tbr: sprang@webrtc.org  # Trivial change in video/
Bug: webrtc:3380
Change-Id: Iaeb6da2fb68991225fe9086ddddd4a553e1620b4
Reviewed-on: https://webrtc-review.googlesource.com/c/107890
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25554}

modules/video_coding/jitter_buffer.h

@@ -35,7 +35,6 @@ enum VCMNackMode { kNack, kNoNack };
 
 // forward declarations
 class Clock;
-class EventFactory;
 class EventWrapper;
 class VCMFrameBuffer;
 class VCMPacket;