Changing lxd storage backend to btrfs Bug #1096

Changing the juju version to 2.7.6

Change-Id: I8b90bc69d7ef830767acce9d6c778a92fe9f73a6
Signed-off-by: Felipe Vicens <felipe.vicens@atos.net>
diff --git a/installers/lxd-preseed.conf b/installers/lxd-preseed.conf
index 82ed8dc..15a9594 100644
--- a/installers/lxd-preseed.conf
+++ b/installers/lxd-preseed.conf
@@ -26,7 +26,7 @@
     size: 100GB
   description: ""
   name: default
-  driver: zfs
+  driver: btrfs
 profiles:
 - config: {}
   description: ""