Fix the nightly test failure for sequence level down-sample filter selection

There is a nightly test failure after !1370, this MR is fixing the related nightly test failures by correcting the condition of identifying a IDR frame.
diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index 657564f..2198d88 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -3849,10 +3849,7 @@
   }
 #endif  // CONFIG_IBC_SR_EXT
   const bool compute_ds_filter =
-      ((cpi->common.current_frame.frame_type == KEY_FRAME &&
-        cpi->common.show_frame) ||
-       cpi->common.current_frame.frame_type == S_FRAME) &&
-      !cpi->common.show_existing_frame;
+      cpi->common.current_frame.frame_type == KEY_FRAME && !cpi->no_show_fwd_kf;
   if (compute_ds_filter) {
     av1_set_downsample_filter_options(cpi);
   }
diff --git a/av1/encoder/firstpass.c b/av1/encoder/firstpass.c
index 869d84b..818e8e2 100644
--- a/av1/encoder/firstpass.c
+++ b/av1/encoder/firstpass.c
@@ -1079,10 +1079,7 @@
   }
 
   const bool compute_ds_filter =
-      ((cpi->common.current_frame.frame_type == KEY_FRAME &&
-        cpi->common.show_frame) ||
-       cpi->common.current_frame.frame_type == S_FRAME) &&
-      !cpi->common.show_existing_frame;
+      cpi->common.current_frame.frame_type == KEY_FRAME && !cpi->no_show_fwd_kf;
   if (compute_ds_filter) {
     av1_set_downsample_filter_options(cpi);
   }