twingate-connector: perform real apt upgrade during update flow (#13959)

* fix(twingate-connector): perform real apt upgrade during update flow

The update path used ensure_dependencies, which only installs missing
packages and does not upgrade already installed ones. As a result, users
could see 'Updated successfully' even when a newer twingate-connector
version was available.

Switch update_script to a real package update flow:
- ensure apt is healthy
- refresh apt metadata
- install/upgrade twingate-connector via retry helper
- restart service

This aligns behavior with Twingate's documented upgrade process.

* Update twingate-connector.sh

ct/twingate-connector.sh

@@ -29,8 +29,9 @@ function update_script() {
     exit
   fi
 
-  msg_info "Updating ${APP}"
-  ensure_dependencies twingate-connector
+  msg_info "Updating Twingate Connector"
+  $STD apt update
+  $STD apt install -y --only-upgrade twingate-connector
   $STD systemctl restart twingate-connector
   msg_ok "Updated successfully!"
   exit