[backport 1.26] fix: don't immediately close missing nodes dialog if manager is disabled (#5648)

Backport of #5647 to `core/1.26`

Automatically created by backport workflow.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5648-backport-1-26-fix-don-t-immediately-close-missing-nodes-dialog-if-manager-is-disabled-2736d73d3650815dba5ac53f6d4578b5)
by [Unito](https://www.unito.io)

Co-authored-by: Christian Byrne <cbyrne@comfy.org>

src/components/dialog/content/LoadWorkflowWarning.vue

@@ -138,7 +138,7 @@ const allMissingNodesInstalled = computed(() => {
 })
 // Watch for completion and close dialog
 watch(allMissingNodesInstalled, async (allInstalled) => {
-  if (allInstalled) {
+  if (allInstalled && showInstallAllButton.value) {
     // Use nextTick to ensure state updates are complete
     await nextTick()