Make max_connections and innodb_buffer_pool_size configurable
through soft params instead of hard.

Change-Id: Id0bb8f6b6091289275864bf4dd6a6890d11b4782

Galera master installation hangs on installation
mysql-server-wsrep-5.6. It seems that log_error is not working,
because of next message: "mysqld_safe Can't log to error log and
syslog at the same time. Remove all --log-error configuration
options for --syslog to take effect." Using "syslog = yes" instead
of log_error makes it works without any other changes.

Change-Id: I39a8a87ed048557c19f3843b97c75469385e4978
Closes-bug: PROD-9065