Add icon select to manual trigger (#12724)

## After

<img width="1220" alt="image"
src="https://github.com/user-attachments/assets/98a73aae-80d7-4e92-93d3-be13210da88b"
/>

<img width="1131" alt="image"
src="https://github.com/user-attachments/assets/9919e415-4355-4995-8979-9055b821f1e9"
/>

<img width="1300" alt="image"
src="https://github.com/user-attachments/assets/27f11cb3-d72c-468a-a641-8414172b9b54"
/>

<img width="1353" alt="image"
src="https://github.com/user-attachments/assets/2f0037f2-fe17-48b6-b7e6-c7528687a5fd"
/>

packages/twenty-server/src/engine/workspace-manager/standard-objects-prefill-data/prefill-workflows.ts

@@ -63,7 +63,7 @@ export const prefillWorkflows = async (
         trigger: JSON.stringify({
           name: 'Launch manually',
           type: 'MANUAL',
-          settings: { outputSchema: {} },
+          settings: { outputSchema: {}, icon: 'IconUserPlus' },
         }),
         steps: JSON.stringify([
           {