Fix password property in SSL tests

The new test setup has no password so the value is null. This
patch fixes the SSL tests to not set the password in the connection
properties if it is null.

src/test/java/org/mariadb/jdbc/SSLValidationTest.java

@@ -68,7 +68,9 @@ private Connection createConnection(Properties info) throws SQLException {
 		String jdbcUrl = connURI;
 		Properties connProps = new Properties(info);
 		connProps.setProperty("user", username);
-		connProps.setProperty("password", password);
+		if( password != null ) {
+		    connProps.setProperty("password", password);
+		}
 		return openNewConnection(jdbcUrl, connProps);
 	}