I need to use standard mysql, in plesk it says everywhere that it is mysql but when I login to console it says mariadb. I understand that it is very similar but this plesk will be hosting staging systems so they must use exactly the technology that the product servers use.
Is it possible to do it somehow using the web interface or do I have to manually install it from console?
As I see it's impossible because plesk-mysql-server package has explicit dependency for mariadb-server.
Yes, you can solve this with --force, but it means further troubles with plesk updates and upgrades.
If you need DB server for some application you can install it on separate server and register it as remote DB server in Tool&Settings > Database Servers.