[FEATURE] Cascade fe_group changes with extendToSubpages (reindex + cleanup)

### Summary
When a parent page’s `fe_group` changes and `extendToSubpages=1` is set, access rules effectively change for descendants as well. This PR ensures the index reflects those changes by triggering subtree reindexing and removing stale access variants.

### What this PR does
- Adds a `changeSet` wildcard (`'*'`) in `AbstractUpdateHandler` to match “any change” of a field, because `fe_group` diffs are non-trivial.
- Introduces trigger `extendToSubpageEnabledAndFeGroupWasChanged` in `DataUpdateHandler` and `GarbageHandler`:
  - If `extendToSubpages=1` and `fe_group` changed → enqueue reindex for descendants (subtree) and clean up outdated access variants/documents.

### How to test
1) Create a small tree: parent **P** with `extendToSubpages=1`, children **C1/C2** inheriting access (no local `fe_group`).
2) Index once so all pages are present.
3) Change **P**’s `fe_group` (e.g., add/remove a frontend group).
4) Expected: subtree pages are queued for reindex; outdated access variants/documents are removed.  
   (Before this PR: descendants did not reliably reindex; stale variants remained.)

Fixes: #4399

Author: DavRet

Classes/Domain/Index/Queue/UpdateHandler/AbstractUpdateHandler.php

@@ -262,6 +262,13 @@ protected function getAllChangeSetValuesMatch(array $triggerConfiguration, array
             return true;
         }
 
+        // Return true if triggerConfiguration field value is '*' and it's key is in changedFields array
+        foreach ($triggerConfiguration['changeSet'] as $key => $value) {
+            if ($value === '*' && array_key_exists($key, $changedFields)) {
+                return true;
+            }
+        }
+
         $diff = array_diff_assoc($triggerConfiguration['changeSet'], $changedFields);
         return empty($diff);
     }

Classes/Domain/Index/Queue/UpdateHandler/DataUpdateHandler.php

@@ -92,6 +92,11 @@ class DataUpdateHandler extends AbstractUpdateHandler
         'no_search_sub_entriesFlagWasAdded' => [
             'changeSet' => ['no_search_sub_entries' => '0'],
         ],
+        // the current page has the field "extendToSubpages" enabled and the field "fe_group" was changed
+        'extendToSubpageEnabledAndFeGroupWasChanged' => [
+            'currentState' =>  ['extendToSubpages' => '1'],
+            'changeSet' => ['fe_group' => '*'],
+        ],
     ];
 
     protected MountPagesUpdater $mountPageUpdater;

Classes/Domain/Index/Queue/UpdateHandler/GarbageHandler.php

@@ -64,6 +64,11 @@ class GarbageHandler extends AbstractUpdateHandler
         'no_search_sub_entriesFlagWasAdded' => [
             'changeSet' => ['no_search_sub_entries' => '1'],
         ],
+        // the current page has the field "extendToSubpages" enabled and the field "fe_group" was changed
+        'extendToSubpageEnabledAndFeGroupWasChanged' => [
+            'currentState' =>  ['extendToSubpages' => '1'],
+            'changeSet' => ['fe_group' => '*'],
+        ],
     ];
 
     /**