fix(editor): Prevent canvas undo/redo when NDV is open (#8118)

## Summary
Preventing canvas undo/redo while NDV or any modal is open. We already
had a NDV open check in place but looks like it was broken by unreactive
ref inside `useHistoryHelper` composable.
This PR fixes this by using store getter directly inside the helper
method and adds modal open check.

## Related tickets and issues
Fixes ADO-657

## Review / Merge checklist
- [ ] PR title and summary are descriptive. **Remember, the title
automatically goes into the changelog. Use `(no-changelog)` otherwise.**
([conventions](https://github.com/n8n-io/n8n/blob/master/.github/pull_request_title_conventions.md))
- [ ] [Docs updated](https://github.com/n8n-io/n8n-docs) or follow-up
ticket created.
- [ ] Tests included.
> A bug is not considered fixed, unless a test is added to prevent it
from happening again.
   > A feature is not complete without tests.

packages/editor-ui/src/components/AboutModal.vue

@@ -47,7 +47,12 @@
 
 		<template #footer>
 			<div class="action-buttons">
-				<n8n-button @click="closeDialog" float="right" :label="$locale.baseText('about.close')" />
+				<n8n-button
+					@click="closeDialog"
+					float="right"
+					:label="$locale.baseText('about.close')"
+					data-test-id="close-about-modal-button"
+				/>
 			</div>
 		</template>
 	</Modal>