There are several obvious issues in what you posted, to so with ulimit. You need to look at your service scripts and make sure that they set suitable limits for what you are configuring in my.cnf.
Are you using the CentOS 8 bundled MariaDB 10.3 or the packages from the MariaDB repositories?
Your journalctl output seems incomplete. systemctl status output may also be useful (make sure neither is truncated in width).
Comment out all of your tuning options and see if it starts then. Unless you know _exactly_ what you are doing or had somebody who _really_ knows what they are doing change any options other than innodb_buffer_pool_size, you should probably leave them at defaults.