Rename deprecated/unsupported options in my.cnf.pre

Change-Id: Ib3b1652ec0c8fd359cfb8008f45b002101885b1b
Closes-Bug: https://mirantis.jira.com/browse/PROD-19688

galera/files/my.cnf.pre

 lc-messages-dir	= /usr/share/mysql
 skip-external-locking
 bind-address		= 127.0.0.1
-key_buffer		= 16M
+key_buffer_size		= 16M
 max_allowed_packet	= 16M
 thread_stack		= 192K
 thread_cache_size       = 8
-myisam-recover         = BACKUP
+myisam-recover-options  = BACKUP
 query_cache_limit	= 1M
 query_cache_size        = 16M
 log_error = /var/log/mysql/error.log