IssueTracker

Issue summary:
Configuration option  to specify the disk type and capacity on the node pool while creating a Dataproc cluster on GKE. As this option was not present in available settings. (https://cloud.google.com/dataproc/docs/guides/dpgke/dataproc-gke-nodepools#node_pool_settings)

Use Case:
As there is no option to specify the disk type and capacity it enforces  to create a nodes with 500GB SSD, which is
- Too expensive, and underutilized
-Getting out of resource usage quota.

Steps to reproduce:
1. Create a new node pool while creating a dataproc cluster on GKE  but there is no option to specify the disk type and capacity.
2. Create a node pool in GKE and specify the disk type and capacity and then use the node pool while creating dataproc cluster on GKE by selecting  reuse existing node pool features  then you will get the following error: NodePool 'default-pool' was not created by Dataproc.
3. You can also try step 2 using gcloud CLI and you will get the same error as mentioned in step 2.

What you expected to happen:
An option to specify the disk type and capacity  for node pool while creating a Dataproc cluster on GKE.