fix(velero): drop the CSI plugin (#2891)

Since 3ae3e17, we upgraded the Velero chart to v7 but this requires us to drop the CSI plugin. Without this change, velero is crashlooping due to a duplicat plugin registration

modules/aws/velero.tf

@@ -56,12 +56,6 @@ initContainers:
      volumeMounts:
        - mountPath: /target
          name: plugins
-   - name: velero-plugin-for-csi
-     image: velero/velero-plugin-for-csi:v0.7.1
-     imagePullPolicy: IfNotPresent
-     volumeMounts:
-       - mountPath: /target
-         name: plugins
 VALUES
 
 }