Fix missing lxd key

manifest.toml

@@ -59,8 +59,8 @@ ram.runtime = "50M"
     [install.backend]
     ask.en = "Should you use LXD or Incus (LXD support will be removed soon)"
     type = "select"
-    choices = ["lxd", "incus"]
-    default = "incus"
+    choices = ["lxd"]
+    default = "lxd"
 
 [resources]
     [resources.system_user]

scripts/upgrade

@@ -54,7 +54,7 @@ if [[ -z "${context:-}" ]]; then
 fi
 
 if [[ -z "${cluster:-}" ]]; then
-    if incus cluster list >/dev/null 2>&1; then
+    if lxc cluster list >/dev/null 2>&1; then
         cluster=1
     else
         cluster=0
@@ -62,6 +62,11 @@ if [[ -z "${cluster:-}" ]]; then
     ynh_app_setting_set --app="$app" --key="cluster" --value="$cluster"
 fi
 
+if [[ -z "${backend:-}" ]]; then
+    backend=lxd
+    ynh_app_setting_set --app="$app" --key="lxd" --value="$lxd"
+fi
+
 # Values now use underscore
 if echo "$context" | grep -- -; then
     context=$(echo "$context" | tr - _)