vp9-rtc: Set init noise level based on resoln
vp9-rtc: Set init noise level based on resoln

Avoid the kLow init level for lower resolns.

Change-Id: I1c9968a6891668b5887e35695f2a44158a4b3a18

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