vp8 multi_res_encoder: Ajust some settings in sample encoder.
vp8 multi_res_encoder: Ajust some settings in sample encoder.

Set #threads to default 1 for all streams, change bit allocaton
for 3 temporal layers, and enable denoiser on middle resolution layer.

Change-Id: I4a57adbfdb2c319002b8f3cf359613842dc00d75

mwgoldsmith/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,mwgoldsmith/vpx,mwgoldsmith/libvpx,webmproject/libvpx,mwgoldsmith/vpx,mwgoldsmith/libvpx,mwgoldsmith/vpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,mwgoldsmith/vpx,mwgoldsmith/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,mwgoldsmith/vpx,webmproject/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/vpx