feat(provider/google): Added new disks type for gce in clouddriver (#5914)

Added new disks type for gce in clouddriver.
currently, only can be used pd-standard and pd-ssd.

Co-authored-by: Jason <jason.mcintosh@armory.io>

Author: jangjaelee

clouddriver-google/src/main/groovy/com/netflix/spinnaker/clouddriver/google/model/GoogleDiskType.groovy

@@ -18,6 +18,8 @@ package com.netflix.spinnaker.clouddriver.google.model
 
 public enum GoogleDiskType {
   PD_STANDARD("pd-standard", true),
+  PD_EXTREME("pd-extreme", true),    
+  PD_BALANCED("pd-balanced", true),    
   PD_SSD("pd-ssd", true),
   LOCAL_SSD("local-ssd", false),
   HYPERDISK_BALANCED("hyperdisk-balanced", true)