Remove useless attachToDocument property

attachToDocument property is not needed

spec/frontend/sidebar/assignees_spec.js

@@ -15,7 +15,6 @@ describe('Assignee component', () => {
   const createWrapper = (propsData = getDefaultProps()) => {
     wrapper = mount(Assignee, {
       propsData,
-      attachToDocument: true,
     });
   };
 

spec/frontend/sidebar/components/assignees/assignee_avatar_link_spec.js

@@ -23,7 +23,6 @@ describe('AssigneeAvatarLink component', () => {
     };
 
     wrapper = shallowMount(AssigneeAvatarLink, {
-      attachToDocument: true,
       propsData,
     });
   }

spec/frontend/sidebar/components/assignees/collapsed_assignee_list_spec.js

@@ -16,7 +16,6 @@ describe('CollapsedAssigneeList component', () => {
     };
 
     wrapper = shallowMount(CollapsedAssigneeList, {
-      attachToDocument: true,
       propsData,
     });
   }

spec/frontend/sidebar/components/assignees/uncollapsed_assignee_list_spec.js

@@ -18,7 +18,6 @@ describe('UncollapsedAssigneeList component', () => {
     };
 
     wrapper = mount(UncollapsedAssigneeList, {
-      attachToDocument: true,
       propsData,
     });
   }