Disable intra_y_mode_mask sf for allintra encode

The handling of sf intra_y_mode_mask was added in the
following CL for intra frames.
https://aomedia-review.googlesource.com/c/aom/+/138781.
The sf is disabled as the trade-off is seen to be worse
for allintra encode.

For AVIF still image encode,

          Instruction Count    BD-Rate Loss(%)
cpu-used     Reduction(%)      psnr       ssim
   4           -3.252         -1.5948    -1.7389
   5           -5.155         -1.6144    -1.7165
   6           -2.597         -1.3882    -1.3959

BUG=aomedia:2959

STATS_CHANGED

Change-Id: Ib4eab0610007fe8aecdcf6f9e7c6f45649c8321b

av1/encoder/speed_features.c

diff --git a/av1/encoder/speed_features.c b/av1/encoder/speed_features.c
index bb5ba0b..916a818 100644
--- a/av1/encoder/speed_features.c
+++ b/av1/encoder/speed_features.c
@@ -417,9 +417,6 @@
     sf->intra_sf.intra_uv_mode_mask[TX_16X16] = UV_INTRA_DC_H_V_CFL;
     sf->intra_sf.intra_uv_mode_mask[TX_32X32] = UV_INTRA_DC_H_V_CFL;
     sf->intra_sf.intra_uv_mode_mask[TX_64X64] = UV_INTRA_DC_H_V_CFL;
-    sf->intra_sf.intra_y_mode_mask[TX_16X16] = INTRA_DC_H_V;
-    sf->intra_sf.intra_y_mode_mask[TX_32X32] = INTRA_DC_H_V;
-    sf->intra_sf.intra_y_mode_mask[TX_64X64] = INTRA_DC_H_V;
     sf->intra_sf.prune_chroma_modes_using_luma_winner = 1;
 
     sf->mv_sf.simple_motion_subpel_force_stop = HALF_PEL;