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

Author: didimmova

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

@@ -212,6 +212,11 @@
             min-height: 100% !important;
             border: none !important;
 
+            .igx-input-group__filler,
+            .igx-input-group__notch {
+                border: none !important;
+            }
+
             &::before {
                 content: none !important;
             }