FIX: CI for mysql: Makefile uses environment variable

Makefile

@@ -83,7 +83,7 @@ doc:
 pipeline-test:
 	cp config.defaults .config
 	echo 'DATABASE_USER_HOST_LIST="%,"' >> .config
-	echo "MYSQL_USER_PASSWORD=$MYSQL_ROOT_PASSWORD" >> .config
+	echo "MYSQL_USER_PASSWORD=$(MYSQL_ROOT_PASSWORD)" >> .config
 	echo "MYSQL_HOST=$(SQL_HOST)" >> .config
 	sleep 10
 	make install