fix(webapp): always reload the smart-column sample when the source changes

The load effect skipped the fetch while a previous request was in flight and never retried, so quickly switching source could leave the sample and preview showing the old (or no) source. The effect only fires on open/sampleUrl change, so the guard was unnecessary; drop it.

Author: ericallam

apps/webapp/app/components/runs/v3/AddSmartColumnDialog.tsx

@@ -99,7 +99,7 @@ export function AddSmartColumnDialog({
   }, [organization.slug, project.slug, environment.slug, currentSearch, sampleFiltersKey, source]);
 
   useEffect(() => {
-    if (open && sample.state === "idle") {
+    if (open) {
       sample.load(sampleUrl);
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps