Revert "prod: don't create separate log file."

This reverts commit c2bbe75.

Spring Boot overwrites application log on each startup. It means that we have always lost log
messages from previous startups.

Author: php-coder

src/main/resources/application-prod.properties

@@ -36,6 +36,7 @@ spring.thymeleaf.cache: true
 liquibase.contexts: scheme, init-data, prod-data
 liquibase.change-log: classpath:/liquibase/changelog.xml
 
+logging.file: /data/logs/mystamps.log
 logging.level.: INFO
 logging.level.ru.mystamps: DEBUG