rtc: Disable temporal_filter for screen

screen-content is noiseless so no need for
temporal_filter. Enabling temporal_filter has some
regression in rtc_screen set:
0.35% bdrate loss,  a few clips 1.4 and 1.8% loss.

Change-Id: Ifc062058477d03415dc2bcdd1588509794ba0223

av1/encoder/speed_features.c

diff --git a/av1/encoder/speed_features.c b/av1/encoder/speed_features.c
index 8b9ebaf..df8649a 100644
--- a/av1/encoder/speed_features.c
+++ b/av1/encoder/speed_features.c
@@ -1295,6 +1295,7 @@
     }
   }
   if (cpi->oxcf.tune_cfg.content == AOM_CONTENT_SCREEN) {
+    sf->rt_sf.use_rtc_tf = 0;
     sf->rt_sf.use_comp_ref_nonrd = 0;
     sf->rt_sf.source_metrics_sb_nonrd = 1;
     if (cpi->rc.high_source_sad == 1) {