GUACAMOLE-728: Merge workaround for legacy Connector/J SSL behavior.

Older versions of the MySQL / MariaDB driver do not support the same level of granular SSL/TLS control, and the legacy "useSSL" parameter cannot be specified without breaking the behavior of "sslMode".
diff --git a/extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLAuthenticationProviderModule.java b/extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLAuthenticationProviderModule.java
index aca3f42..4e4f35e 100644
--- a/extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLAuthenticationProviderModule.java
+++ b/extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLAuthenticationProviderModule.java
@@ -87,11 +87,9 @@
         MySQLSSLMode sslMode = environment.getMySQLSSLMode();
         driverProperties.setProperty("sslMode", sslMode.getDriverValue());
         
-        // Set legacy properties
+        // For compatibility, set legacy useSSL property when SSL is disabled.
         if (sslMode == MySQLSSLMode.DISABLED)
             driverProperties.setProperty("useSSL", "false");
-        else
-            driverProperties.setProperty("useSSL", "true");
         
         // Check other SSL settings and set as required
         File trustStore = environment.getMySQLSSLTrustStore();