test(grid): fix failing test

Author: georgianastasov

projects/igniteui-angular/src/lib/grids/grid/grid-summary.spec.ts

@@ -160,9 +160,6 @@ describe('IgxGrid - Summaries #grid', () => {
 
                 const column = grid.getColumnByName('UnitsInStock');
 
-                column.disabledSummaries = [];
-                fixture.detectChanges();
-                tick();
                 GridSummaryFunctions.verifyColumnSummaries(
                     GridSummaryFunctions.getRootSummaryRow(fixture), 3,
                     ['Count', 'Min', 'Max', 'Sum', 'Avg'],