[AAE-10594] Run unit tests in headless mode (#8141)

* AAE-10594 - changed karma configs to run unit tests in headless mode

* AAE-10594 - removed commets

* [AAE-10594] fixed failing test

lib/core/src/lib/clipboard/clipboard.service.spec.ts

@@ -69,7 +69,9 @@ describe('ClipboardService', () => {
     });
 
     it('should notify copy to clipboard with message', () => {
+        spyOn(navigator.clipboard, 'writeText');
         spyOn(notificationService, 'openSnackMessage');
+
         inputElement.value = 'some text';
 
         clipboardService.copyToClipboard(inputElement, 'success');