Hide group control nav if no options present

Closes #19120

app/views/layouts/nav/_group.html.haml

+= render 'layouts/nav/group_settings'
 .scrolling-tabs-container{ class: nav_control_class }
-  = render 'layouts/nav/group_settings'
   .fade-left
     = icon('angle-left')
   .fade-right

app/views/layouts/nav/_group_settings.html.haml

 - if current_user
+  - can_admin_projects = can?(current_user, :admin_group, @group)
   - can_edit = can?(current_user, :admin_group, @group)
   - member = @group.members.find_by(user_id: current_user.id)
   - can_leave = member && can?(current_user, :destroy_group_member, member)
 
-  .controls
-    .dropdown.group-settings-dropdown
-      %a.dropdown-new.btn.btn-default#group-settings-button{href: '#', 'data-toggle' => 'dropdown'}
-        = icon('cog')
-        = icon('caret-down')
-      %ul.dropdown-menu.dropdown-menu-align-right
-        = nav_link(path: 'groups#projects') do
-          = link_to 'Projects', projects_group_path(@group), title: 'Projects'
-        %li.divider
-        - if can_edit
-          %li
-            = link_to 'Edit Group', edit_group_path(@group)
-        - if can_leave
-          %li
-            = link_to polymorphic_path([:leave, @group, :members]),
-              data: { confirm: leave_confirmation_message(@group) }, method: :delete, title: 'Leave group' do
-              Leave Group
+  - if can_admin_projects || can_edit || can_leave
+    .controls
+      .dropdown.group-settings-dropdown
+        %a.dropdown-new.btn.btn-default#group-settings-button{href: '#', 'data-toggle' => 'dropdown'}
+          = icon('cog')
+          = icon('caret-down')
+        %ul.dropdown-menu.dropdown-menu-align-right
+          - if can_admin_projects
+            = nav_link(path: 'groups#projects') do
+              = link_to 'Projects', projects_group_path(@group), title: 'Projects'
+          - if can_edit || can_leave
+            %li.divider
+          - if can_edit
+            %li
+              = link_to 'Edit Group', edit_group_path(@group)
+          - if can_leave
+            %li
+              = link_to polymorphic_path([:leave, @group, :members]),
+                data: { confirm: leave_confirmation_message(@group) }, method: :delete, title: 'Leave group' do
+                Leave Group