Fixed tab not focusing role select in Invite User modal (#1020)

closes #7132
- removed `tabindex` from role selection on invite user field
- removing the tabindex defaults the tabindex to "-1"

app/templates/components/modal-invite-new-user.hbs

@@ -28,7 +28,7 @@
 
         <div class="form-group for-select">
             <label for="new-user-role">Role</label>
-            <span class="gh-select" tabindex="0">
+            <span class="gh-select">
                 {{one-way-select
                     id="new-user-role"
                     name="role"