[v10.4.x] Alerting: Fix max alerts (#87299)

Alerting: Fix max alerts (#87271)

(cherry picked from commit 12fa9e56e6)

Co-authored-by: Gilles De Mey <gilles.de.mey@gmail.com>

public/app/features/alerting/unified/utils/cloud-alertmanager-notifier-types.ts

@@ -322,8 +322,12 @@ export const cloudNotifierTypes: Array<NotifierDTO<CloudNotifierType>> = [
         'The maximum number of alerts to include in a single webhook message. Alerts above this threshold are truncated. When leaving this at its default value of 0, all alerts are included.',
         {
           placeholder: '0',
+          inputType: 'number',
           validationRule: '(^\\d+$|^$)',
-          setValueAs: (value) => (typeof value === 'string' ? parseInt(value, 10) : 0),
+          setValueAs: (value) => {
+            const integer = Number(value);
+            return Number.isFinite(integer) ? integer : 0;
+          },
         }
       ),
       httpConfigOption,