feat(filtering): Remove the viewport styles and unused placeholder selector

Author: MPopov

projects/igniteui-angular/src/lib/core/styles/components/grid/_grid-component.scss

@@ -554,10 +554,6 @@
         @extend %igx-grid__filtering-row--compact !optional;
     }
 
-    @include e(filtering-row-buttons) {
-        @extend %igx-grid__filtering-row-buttons !optional;
-    }
-
     @include e(filtering-row-editing-buttons) {
         @extend %igx-grid__filtering-row-editing-buttons !optional;
     }

projects/igniteui-angular/src/lib/core/styles/components/grid/_grid-theme.scss

@@ -2642,20 +2642,8 @@
         align-items: center;
 
         [igxButton='icon'] {
-            display: none;
-        }
-
-        @media only screen and (max-width: $mobile-view) {
-            [igxButton] {
-                display: none;
-            }
-
-            [igxButton='icon'] {
-                display: flex;
-
-                &:not([disabled]) {
-                    color: --var($theme, 'sorted-header-icon-color');
-                }
+            &:not([disabled]) {
+                color: --var($theme, 'sorted-header-icon-color');
             }
         }
     }

projects/igniteui-angular/src/lib/grids/filtering/base/grid-filtering-row.component.html

@@ -130,12 +130,4 @@
         <igx-icon>close</igx-icon>
         {{filteringService.grid.resourceStrings.igx_grid_filter_row_close}}
     </button>
-
-    <!-- Visible only under 432px viewport  -->
-    <button igxButton="icon" igxRipple (click)="clearFiltering()" [disabled]="disabled" [tabindex]="disabled">
-        <igx-icon>refresh</igx-icon>
-    </button>
-    <button #closeButton igxButton="icon" igxRipple (click)="close()">
-        <igx-icon>close</igx-icon>
-    </button>
 </div>