fixed react warning in Suspense in alert flyout (#77777)

Author: gmmorris

x-pack/plugins/triggers_actions_ui/public/application/sections/alert_form/alert_form.tsx

@@ -244,7 +244,7 @@ export const AlertForm = ({
         ) : null}
       </EuiFlexGroup>
       {AlertParamsExpressionComponent ? (
-        <Suspense fallback={CenterJustifiedSpinner}>
+        <Suspense fallback={<CenterJustifiedSpinner />}>
           <AlertParamsExpressionComponent
             alertParams={alert.params}
             alertInterval={`${alertInterval ?? 1}${alertIntervalUnit}`}