Support to configure ephemeral-storage for data mover pods and repo maintenance pods

[Lyndon-Li]

Data mover pods and repo maintenance pods may use pod ephemeral-storage for cache if cache volume is not configured.
Then when cache volume is not configured, users may need to configure the ephemeral-storage for these pods in below cases:

• The default pod ephemeral-storage is very small in the cluster. This would cause the pods failure because of running out of ephemeral-storage
• Some nodes are with limited disk spaces in the cluster. An ephemeral-storage configuration in the pods helps the scheduler to find the right node to run the pods