[feature request]improve configuration of concurrent yurtappdaemon workers

[rambohe]

What would you like to be added:

please refer to pull request #1906 and improve yurtappdaemon-workers configuration for yurtappdaemon controller in yurt-manager component.

openyurt/pkg/yurtmanager/controller/yurtappdaemon/yurtappdaemon_controller.go

Line 64 in ed20955

 flag.IntVar(&concurrentReconciles, "yurtappdaemon-workers", concurrentReconciles, "Max concurrent workers for YurtAppDaemon controller.") 

others
/kind feature

[Leo Huang]

/assign