Add functional test for search embeddable in Discover

[ananzh]

In OSD, we don't have enough tests covering embeddable. For example, we find this bug which shows when dashboard loads a saved search, sort state is not loaded. Propose to add more tests:

• Add unit test for search embeddable in Discover

• Unit test should test the internal logic of the SearchEmbeddable class, ensuring that individual methods behave as expected under various conditions

• Add functional test for search embeddable in Discover

• Embeddable Rendering: Test that the embeddable renders correctly in the dashboard and displays the expected data. Test sort, columns, filter and etc are loaded correctly.
• User Interactions: Verify that interactions (e.g., changing sort order, adding/removing columns) update the embeddable and the URL state.
• Data Fetching and Display: Ensure that changing filters, queries, or time ranges updates the displayed data as expected.

[ananzh]

duplicate