Make DatabaseMysqlBase::insertSelect() safer to use

Make DatabaseMysqlBase::insertSelect() safer to use

Certain server configurations, including the current MariaDB defaults,
make INSERT SELECT unsafe for replication in MySQL/MariaDB. When the
server configuration is not known to be safe, force the use of the
non-native implementation. Note this only has effect in CLI mode, as
non-CLI mode already forces the non-native implementation since
I2dba6024.

Also, native INSERT SELECT won't be safe with any statement-based
replication method if the order of rows in the SELECT is not
deterministic. Add a warning to the method's documentation pointing this
out.

Change-Id: I9173f6559809bd01830bd0a9f443c7269cc58ce2