Fix SQL syntax for MySQL 8.0.

'GRANT ... REQUIRE SSL' was deprecated in MySQL 5.7.6 and removed in MySQL 8.0. Instead of creating multiple init.sql scripts, we use opt-in syntax so only the latest servers will require SSL for this user account.

Author: bgrainger

.ci/server/init.sql

@@ -1,6 +1,6 @@
 CREATE USER 'mysqltest'@'%' IDENTIFIED BY 'test;key=\"val'; GRANT ALL ON *.* TO mysqltest;
 CREATE USER 'no_password'@'localhost';
 CREATE USER 'no_password'@'172.17.0.1';
-CREATE USER 'ssltest'@'%' IDENTIFIED BY 'test'; GRANT ALL PRIVILEGES ON *.* TO 'ssltest'@'%' REQUIRE SSL;
+CREATE USER 'ssltest'@'%' IDENTIFIED BY 'test' /*!50706 REQUIRE SSL */; GRANT ALL PRIVILEGES ON *.* TO 'ssltest'@'%';
 SET GLOBAL max_allowed_packet=104857600;