Remove a custom validation in the LDAP Group link API

The validation is now done by Grape since 16a8b5c6.
Signed-off-by: Rémy Coutable <remy@rymai.me>

lib/api/helpers.rb

@@ -126,10 +126,6 @@ module API
       authorize! :push_code, user_project
     end
 
-    def validate_access_level?(level)
-      Gitlab::Access.options_with_owner.values.include? level.to_i
-    end
-
     def authorize_admin_project
       authorize! :admin_project, user_project
     end

lib/api/ldap_group_links.rb

@@ -18,9 +18,6 @@ module API
       post ":id/ldap_group_links" do
         group = find_group(params[:id])
         authorize! :admin_group, group
-        unless validate_access_level?(params[:group_access])
-          render_api_error!("Wrong group access level", 422)
-        end
 
         ldap_group_link = group.ldap_group_links.new(declared_params(include_missing: false))
         if ldap_group_link.save