anaconda: align with imgbased layout

imgbased changed layout with oVirt/imgbased#3 .
Aligning initial storage layout to match it.

Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>

data/ovirt.conf

@@ -24,18 +24,20 @@ default_partitioning =
     /              (min 6 GiB)
     /home          (size 1 GiB)
     /tmp           (size 1 GiB)
-    /var           (size 15 GiB)
+    /var           (size 5 GiB)
     /var/crash     (size 10 GiB)
     /var/log       (size 8 GiB)
     /var/log/audit (size 2 GiB)
+    /var/tmp       (size 10 GiB)
     swap
 
 [Storage Constraints]
 root_device_types = LVM_THINP
 must_not_be_on_root = /var
 req_partition_sizes =
-    /var   10 GiB
-    /boot  1  GiB
+    /var     5  GiB
+    /var/tmp 10 GiB
+    /boot    1  GiB
 
 [User Interface]
 help_directory = /usr/share/anaconda/help/centos