Fix accessibility bug in SelectRole, ChangeRole combo boxes labels (#8253)

Author: skofman1

src/NuGetGallery/Views/Organizations/_OrganizationAccountManageMembers.cshtml

@@ -40,7 +40,7 @@
                             <input id="new-member-textbox" class="form-control" placeholder="Add existing NuGet.org user" data-bind="textInput: NewMemberUsername, submit: AddMember" aria-label="Enter username to add member"  />
                         </div>
                         <div class="col-xs-3">
-                            <select class="form-control" data-bind="value: AddMemberRole, options: RoleNames" aria-label="Select new member role">
+                            <select class="form-control" data-bind="value: AddMemberRole, options: RoleNames" aria-labelledby="RoleNames">
                             </select>
                         </div>
                         <div class="text-right col-xs-1">
@@ -73,7 +73,7 @@
                     <div class="col-xs-3">
                         @if (Model.CanManageMemberships)
                         {
-                            <select class="form-control" aria-label="Change member role"
+                            <select class="form-control" aria-labelledby="OrganizationViewModel.RoleNames"
                                     data-bind="value: SelectedRole, options: OrganizationViewModel.RoleNames, event: { change: ToggleIsAdmin }">
                             </select>
                         }