[Dashboard] [Controls] Fix dashboard reset when initial state has no controls (#159404)

## Summary

Consider taking the following steps:

1. Create a new dashboard and save it
2. Add a control and, without saving,
3. Reset the changes to the dashboard

### Before 
Before this PR, we were not updating the control group input if the
`lastSavedControlGroupInput` was `undefined` (which only happens when a
dashboard has **never** been saved with any controls and/or edits to the
control group settings) - this caused a problem when trying to reset a
dashboard from having controls back to the state where
`lastSavedControlGroupInput` was `undefined` because the **dashboard's**
input would get updated as expected (i.e. the dashboard would think it
no longer has any controls), but the control group's input wouldn't get
updated (i.e. the control group would think it **still has** controls).

Because of this discrepancy, the control would stick around until you
refreshed the dashboard:


c9da58dc-3373-493d-9bba-5d2540c19560

### After
Now, after this PR, I fixed this by resetting back to the default
control group input if `lastSavedControlGroupInput` is `undefined` on
reset:


e41838e6-6dbe-47a1-bea7-28f20eddcf80


### Checklist

- [x] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)

### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

src/plugins/dashboard/public/dashboard_container/embeddable/dashboard_container.tsx

@@ -28,7 +28,10 @@ import { reportPerformanceMetricEvent } from '@kbn/ebt-tools';
 import { KibanaThemeProvider } from '@kbn/kibana-react-plugin/public';
 import type { ControlGroupContainer } from '@kbn/controls-plugin/public';
 import type { KibanaExecutionContext, OverlayRef } from '@kbn/core/public';
-import { persistableControlGroupInputIsEqual } from '@kbn/controls-plugin/common';
+import {
+  getDefaultControlGroupInput,
+  persistableControlGroupInputIsEqual,
+} from '@kbn/controls-plugin/common';
 import { ExitFullScreenButtonKibanaProvider } from '@kbn/shared-ux-button-exit-full-screen';
 
 import {
@@ -326,10 +329,9 @@ export class DashboardContainer extends Container<InheritedChildInput, Dashboard
 
     if (
       this.controlGroup &&
-      lastSavedControlGroupInput &&
       !persistableControlGroupInputIsEqual(this.controlGroup.getInput(), lastSavedControlGroupInput)
     ) {
-      this.controlGroup.updateInput(lastSavedControlGroupInput);
+      this.controlGroup.updateInput(lastSavedControlGroupInput ?? getDefaultControlGroupInput());
     }
 
     // if we are using the unified search integration, we need to force reset the time picker.