[ResponseOps][Rules] Add loading state to rule params data views sele…

…ctor (elastic#203654)

## Summary

Introduces a loading state in the data views select popover and renders
a loading indicator when DVs are not available yet. This makes sure that
even if the `savedObjectsClient.find` call of the data views service
takes a long time, we don't show an empty popover in the meantime.


https://github.com/user-attachments/assets/5bbe0c68-3ceb-4d7f-91fd-357db4caa5c1

## References

Fixes elastic#198502 

## Release note

Fix race condition in alerting rules data view selector

x-pack/plugins/stack_alerts/public/rule_types/components/data_view_select_popover.tsx

@@ -18,6 +18,7 @@ import {
   EuiPopover,
   EuiPopoverFooter,
   EuiPopoverTitle,
+  EuiLoadingSpinner,
   EuiText,
   useEuiPaddingCSS,
   useIsWithinBreakpoints,
@@ -63,6 +64,7 @@ export const DataViewSelectPopover: React.FunctionComponent<DataViewSelectPopove
   onSelectDataView,
   onChangeMetaData,
 }) => {
+  const [loadingDataViews, setLoadingDataViews] = useState(false);
   const [dataViewItems, setDataViewsItems] = useState<DataViewListItemEnhanced[]>([]);
   const [dataViewPopoverOpen, setDataViewPopoverOpen] = useState(false);
 
@@ -71,7 +73,7 @@ export const DataViewSelectPopover: React.FunctionComponent<DataViewSelectPopove
   const closeDataViewEditor = useRef<() => void | undefined>();
 
   const allDataViewItems = useMemo(
-    () => [...dataViewItems, ...metadata.adHocDataViewList.map(toDataViewListItem)],
+    () => [...(dataViewItems ?? []), ...metadata.adHocDataViewList.map(toDataViewListItem)],
     [dataViewItems, metadata.adHocDataViewList]
   );
 
@@ -87,10 +89,16 @@ export const DataViewSelectPopover: React.FunctionComponent<DataViewSelectPopove
   );
 
   const loadPersistedDataViews = useCallback(async () => {
-    const ids = await dataViews.getIds();
-    const dataViewsList = await Promise.all(ids.map((id) => dataViews.get(id)));
-
-    setDataViewsItems(dataViewsList.map(toDataViewListItem));
+    setLoadingDataViews(true);
+    try {
+      // Calling getIds with refresh = true to make sure we don't get stale data
+      const ids = await dataViews.getIds(true);
+      const dataViewsList = await Promise.all(ids.map((id) => dataViews.get(id)));
+      setDataViewsItems(dataViewsList.map(toDataViewListItem));
+    } catch (e) {
+      // Error fetching data views
+    }
+    setLoadingDataViews(false);
   }, [dataViews]);
 
   const onAddAdHocDataView = useCallback(
@@ -153,8 +161,10 @@ export const DataViewSelectPopover: React.FunctionComponent<DataViewSelectPopove
     [dataViews, onAddAdHocDataView, onChangeDataView]
   );
 
-  if (!allDataViewItems) {
-    return null;
+  if (loadingDataViews) {
+    // The loading indicator is to make sure we don't render an
+    // empty popover when the DV cache is initially loading
+    return <EuiLoadingSpinner />;
   }
 
   return (