Stop spinner on cleanup & simplify qm set

Call stop_spinner in cleanup() to ensure any active spinner is stopped on exit. Consolidate duplicated qm set branches in ubuntu2604-vm.sh into a single invocation to reduce code duplication and simplify VM disk/serial configuration. Remove the explicit ide2 cloudinit device and redundant cloud-init status messages; setup_cloud_init() is still invoked when USE_CLOUD_INIT is enabled, keeping cloud-init configuration centralized.

misc/vm-core.func

@@ -560,6 +560,7 @@ cleanup_vmid() {
 
 cleanup() {
   local exit_code=$?
+  stop_spinner
   if [[ "$(dirs -p | wc -l)" -gt 1 ]]; then
     popd >/dev/null || true
   fi