fix test for click subscription in events_engine (T1307313)

Author: GoodDayForSurf

packages/devextreme/testing/tests/DevExpress.ui.events/event_nodes_disposing.tests.js

@@ -19,7 +19,6 @@ QUnit.module('event nodes disposing', {
 
 QUnit.test('should not leak memory when subscribing to dxclick on document and clicking elements', function(assert) {
     const done = assert.async();
-    const document = domAdapter.getDocument();
     const testElement = document.getElementById('test-element');
 
     eventsEngine.on(document, clickEventName, () => {});

packages/devextreme/testing/tests/DevExpress.ui.events/eventsEngine.tests.js

@@ -595,7 +595,6 @@ QUnit.test('removing subscriptions should not remove data from elementDataMap if
 
 QUnit.test('should not leak memory when subscribing on document and clicking elements (T1307313)', function(assert) {
     const done = assert.async();
-    const document = domAdapter.getDocument();
     const fixture = document.getElementById('qunit-fixture');
 
     fixture.innerHTML = '<button id="test-element">Test</button>';
@@ -630,7 +629,6 @@ QUnit.test('should not leak memory when subscribing on document and clicking ele
                     `Memory should not leak. Memory diff: ${memoryDiff}B`
                 );
 
-                eventsEngine.off(document, clickEventName);
                 done();
             }, 50);