fix: do not append doc input for scheduled publish job if it's enabled only for globals (#11892)

Fixes https://github.com/payloadcms/payload/issues/11891


Previously, if you had scheduled publish enabled only for globals, not
collections - you'd get an error on `payload generate:types`:
<img width="886" alt="image"
src="https://github.com/user-attachments/assets/78125ce8-bd89-4269-bc56-966d8e0c3968"
/>

This was caused by appending the `doc` field to the scheduled publish
job input schema with empty `collections` array. Now we skip this field
if we don't have any collections.

packages/payload/src/versions/schedule/job.ts

@@ -1,5 +1,6 @@
 // @ts-strict-ignore
 import type { User } from '../../auth/types.js'
+import type { Field } from '../../fields/config/types.js'
 import type { TaskConfig } from '../../queues/config/types/taskTypes.js'
 import type { SchedulePublishTaskInput } from './types.js'
 
@@ -87,11 +88,15 @@ export const getSchedulePublishTask = ({
         name: 'locale',
         type: 'text',
       },
+      ...(collections.length > 0
+        ? [
             {
               name: 'doc',
               type: 'relationship',
               relationTo: collections,
-      },
+            } satisfies Field,
+          ]
+        : []),
       {
         name: 'global',
         type: 'select',