[manila] lower default reserve to 30%

to be aligned with netapp backend monitoring that alerts at 70%
fillgrade.
Otherwise we had a gap where no new provisionings were possible,
but backend operations were not aware.

openstack/manila/templates/shares/_share-netapp.conf.tpl

@@ -86,7 +86,7 @@ netapp_hardware_state = {{ $share.hardware_state | default "live" }}
 {{- if eq 100 (int $share.reserved_share_percentage)}}
 reserved_share_percentage = 100
 {{- else }}
-reserved_share_percentage = {{ $share.reserved_share_percentage | default 40 }}
+reserved_share_percentage = {{ $share.reserved_share_percentage | default 30 }}
 {{- end }}
 
 {{- if eq 100 (int $share.reserved_share_extend_percentage)}}