fix(grid): fix input having notch borders in grid cell

Author: didimmova

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

@@ -211,7 +211,8 @@
             min-height: 100% !important;
             border: none !important;
 
-            .igx-input-group__filler {
+            .igx-input-group__filler,
+            .igx-input-group__notch {
                 border: none !important;
             }