libvpx,vp9_datarate_test: drop one-pass vod mode
libvpx,vp9_datarate_test: drop one-pass vod mode

this test is only useful for realtime mode testing given the number of
frames and that one-pass vod has never been a primary focus for
development.

BUG=webm:1512

Change-Id: I23208393a5fcc5bcf9b267fab4b0d1aad500918a

ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx