When setting FE config default_storage_medium to SSD, and set all BE storage path as SSD.
And table will be stored with storage medium SSD.
But there is a FE config storage_cooldown_second and its default value is 30 days.
So after 30 days, the storage medium of table will be changed to HDD, which is unexpected.
This PR removes the storage_cooldown_second, and use a max value to set the cooldown time of SSD
storage medium when the default_storage_medium is SSD.
6c8ed9135d