Adding cron param for xtrabackup

Change-Id: Ifad8690991498103cd87884d7b1967e68b66acc9
Related: PROD-28173 (PROD:28173)
diff --git a/xtrabackup/client/single.yml b/xtrabackup/client/single.yml
index 25fa6d2..cf88e28 100644
--- a/xtrabackup/client/single.yml
+++ b/xtrabackup/client/single.yml
@@ -6,4 +6,5 @@
     xtrabackup_client_throttle: 0 # disabled
   xtrabackup:
     client:
+      cron: false
       throttle: ${_param:xtrabackup_client_throttle}