In 2.6.0, we added an option called "-directlyAccessNodeLabelStore" to make RM can start with label-configured queue settings. After
YARN-2918, we don't need this option any more, admin can configure queue setting, start RM and configure node label via RMAdminCLI without any error.
In addition, this option is very restrictive, first it needs to run on the same node where RM is running if admin configured to store labels in local disk.
Second, when admin run the option when RM is running, multiple process write to a same file can happen, this could make node label store becomes invalid.