fix(@schematics/angular): use proper variable in functional guard spec

Author: cexbrayat

packages/schematics/angular/guard/type-files/__name@dasherize__.guard.spec.ts.template

@@ -12,6 +12,6 @@ describe('<%= camelize(name) %>Guard', () => {
   });
 
   it('should be created', () => {
-    expect(<%= camelize(name) %>Guard).toBeTruthy();
+    expect(executeGuard).toBeTruthy();
   });
 });