Modify scheduling structure of Connector index (#158640)

# Part of https://github.com/elastic/enterprise-search-team/issues/4628

## Summary

This PR modifies the structure of `scheduling` in index
`.elastic-connectors`.


### Checklist

Delete any items that are not applicable to this PR.

- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

x-pack/plugins/enterprise_search/server/index_management/setup_indices.test.ts

@@ -165,8 +165,24 @@ describe('Setup Indices', () => {
       },
       scheduling: {
         properties: {
-          enabled: { type: 'boolean' },
-          interval: { type: 'text' },
+          access_control: {
+            properties: {
+              enabled: { type: 'boolean' },
+              interval: { type: 'text' },
+            },
+          },
+          incremental: {
+            properties: {
+              enabled: { type: 'boolean' },
+              interval: { type: 'text' },
+            },
+          },
+          full: {
+            properties: {
+              enabled: { type: 'boolean' },
+              interval: { type: 'text' },
+            },
+          },
         },
       },
       service_type: { type: 'keyword' },

x-pack/plugins/enterprise_search/server/index_management/setup_indices.ts

@@ -154,8 +154,24 @@ const connectorMappingsProperties: Record<string, MappingProperty> = {
   },
   scheduling: {
     properties: {
-      enabled: { type: 'boolean' },
-      interval: { type: 'text' },
+      access_control: {
+        properties: {
+          enabled: { type: 'boolean' },
+          interval: { type: 'text' },
+        },
+      },
+      incremental: {
+        properties: {
+          enabled: { type: 'boolean' },
+          interval: { type: 'text' },
+        },
+      },
+      full: {
+        properties: {
+          enabled: { type: 'boolean' },
+          interval: { type: 'text' },
+        },
+      },
     },
   },
   service_type: { type: 'keyword' },