test(backup): drop unnecessary PARENT_BACKUP_ID stub in sweep-pending-parent test

deletingLeafSweepsUpDeletePendingParent stubbed the leaf's PARENT_BACKUP_ID
but production never reads it on this path:

  - findLiveChildren(leaf) iterates the sibling list and reads each *other*
    backup's PARENT_BACKUP_ID against leaf.getUuid() — never the leaf's own.
  - getChainOrderedLeafToRoot (introduced in 096bef1) walks the chain by
    CHAIN_ID + CHAIN_POSITION; the legacy findChainParent → PARENT_BACKUP_ID
    walk is bypassed for the sweep.

Same UnnecessaryStubbingException pattern as 9f4d61f; the parent's
PARENT_BACKUP_ID stub IS still used (findLiveChildren reads it) so it stays.

Unblocks CI for #13074.

Author: jmsperu

plugins/backup/nas/src/test/java/org/apache/cloudstack/backup/NASBackupProviderTest.java

@@ -596,10 +596,8 @@ public void deletingLeafSweepsUpDeletePendingParent()
         // ordered chain — getChainOrderedLeafToRoot sorts by CHAIN_POSITION descending.
         BackupDetailVO leafChainId = new BackupDetailVO(51L, NASBackupChainKeys.CHAIN_ID, "chain-1", true);
         BackupDetailVO leafChainPos = new BackupDetailVO(51L, NASBackupChainKeys.CHAIN_POSITION, "1", true);
-        BackupDetailVO leafParent = new BackupDetailVO(51L, NASBackupChainKeys.PARENT_BACKUP_ID, "parent-uuid", true);
         Mockito.when(backupDetailsDao.findDetail(51L, NASBackupChainKeys.CHAIN_ID)).thenReturn(leafChainId);
         Mockito.when(backupDetailsDao.findDetail(51L, NASBackupChainKeys.CHAIN_POSITION)).thenReturn(leafChainPos);
-        Mockito.when(backupDetailsDao.findDetail(51L, NASBackupChainKeys.PARENT_BACKUP_ID)).thenReturn(leafParent);
 
         // Parent is the tombstoned full anchor (CHAIN_POSITION=0).
         BackupDetailVO parentChainId = new BackupDetailVO(50L, NASBackupChainKeys.CHAIN_ID, "chain-1", true);