Fix UT failure in BackupManagerTest

Author: abh1sar

server/src/test/java/org/apache/cloudstack/backup/BackupManagerTest.java

@@ -626,6 +626,7 @@ public void testCreateBackupLimitReached() throws ResourceAllocationException {
 
         CreateBackupCmd cmd = Mockito.mock(CreateBackupCmd.class);
         when(cmd.getVmId()).thenReturn(vmId);
+        when(cmd.getScheduleId()).thenReturn(scheduleId);
 
         backupManager.createBackup(cmd);