Widget preview stops functioning after editing an existing data point graph widget

[rahulc8y]

While the initial creation and configuration of the widget works as expected, the preview functionality becomes non-operational when attempting to edit an existing widget.

Steps to Reproduce:

1. Navigate to any dashboard in the Cockpit application
2. Click "Add Widget" and select "Data Point Graph"
3. Configure the widget with desired data points and settings
4. Save the widget (Preview works correctly at this stage)
5. Click "Edit" on the existing Data Point Graph widget
6. Observe that the preview functionality is no longer working
7. Save the widget again
8. Note that no data is displayed until the date range is manually changed

Expected Behavior: The preview functionality should: Remain operational during both initial creation and subsequent edits
Actual Behavior: Preview functionality stops working completely when editing an existing Data Point Graph widget

Video :
https://github.com/user-attachments/assets/8d7bf076-8c0f-4164-94b0-12223e6ff264