CA-409710: Reduce the default metadata backups count

The current default count of metadata backup files is 25. This number is too
many. For the customer in XSI-1873, the backup disk is 500 MB, and each backup
file is about 35 MB. So it can't keep 25 backup files.

A quick solution is to reduce the default count of metadata backup files to 12.

Signed-off-by: Bengang Yuan <[email protected]>

Author: BengangY

scripts/xe-backup-metadata

@@ -24,7 +24,7 @@ if [ "${master_uuid}" != "${INSTALLATION_UUID}" ]; then
    exit 1
 fi
 
-history_kept=25
+history_kept=12
 metadata_version=1
 debug=/bin/true