Standardize CT update backup handling (#15937)

ct/metube.sh

@@ -48,14 +48,11 @@ function update_script() {
     systemctl stop metube
     msg_ok "Stopped Service"
 
-    msg_info "Backing up Old Installation"
-    if [[ -d /opt/metube_bak ]]; then
-      rm -rf /opt/metube_bak
-    fi
-    mv /opt/metube /opt/metube_bak
-    msg_ok "Backup created"
+    create_backup /opt/metube/.env
 
-    fetch_and_deploy_gh_release "metube" "alexta69/metube" "tarball" "latest"
+    CLEAN_INSTALL=1 fetch_and_deploy_gh_release "metube" "alexta69/metube" "tarball" "latest"
+
+    restore_backup
 
     msg_info "Building Frontend"
     cd /opt/metube/ui
@@ -75,13 +72,6 @@ function update_script() {
     $STD uv sync
     msg_ok "Installed Backend"
 
-    msg_info "Restoring .env"
-    if [[ -f /opt/metube_bak/.env ]]; then
-      cp /opt/metube_bak/.env /opt/metube/.env
-    fi
-    rm -rf /opt/metube_bak
-    msg_ok "Restored .env"
-
     if grep -q 'pipenv' /etc/systemd/system/metube.service; then
       msg_info "Patching systemd Service"
       cat <<EOF >/etc/systemd/system/metube.service