set Azure Disk CSI driver migration as implemented

Author: andyzhangx

keps/sig-storage/1490-csi-migration-azuredisk/kep.yaml

@@ -14,7 +14,7 @@ editor: "@Jiawei0227"
 creation-date: 2022-01-05
 last-updated: 2022-01-05
 disable-supported: true
-status: implementable
+status: implemented
 see-also:
   - "https://github.com/kubernetes/community/blob/master/contributors/design-proposals/storage/csi-migration.md"
 prr-approvers:
@@ -52,4 +52,4 @@ feature-gates:
 # The following PRR answers are required at beta release
 metrics:
   - csi_sidecar_duration_operation
-  - storage_operation_duration_seconds
+  - storage_operation_duration_seconds