MariaDB server fails to start when basedir set to anything

Server fails to start when basedir is set in config file, even if it's set to a default value of /usr.

Steps to reproduce:

• install mariadb-server
• set basedir=/usr in config
• start service

Error:
2024-02-27 11:32:51 0 [ERROR] mariadbd: Can't open shared library '/usr/provider_lz4.so' (errno: 2, cannot open shared object file: No such file or directory)
2024-02-27 11:32:51 0 [ERROR] Couldn't load plugins from 'provider_lz4.so'.
2024-02-27 11:32:51 0 [ERROR] /usr/libexec/mariadbd: unknown variable 'provider_lz4=force_plus_permanent'
2024-02-27 11:32:51 0 [ERROR] Aborting

Specifically, it's /usr/libexec/mariadb-prepare-db-dir that is failing.

Steps to reproduce with docker:

• docker run --rm -it quay.io/centos/centos:stream9 bash
• dnf install -y mariadb-server
• echo -e "[mysqld]\nbasedir=/usr" >> /etc/my.cnf.d/server.cnf
• /usr/libexec/mariadb-prepare-db-dir mariadb
• cat /var/log/mariadb/mariadb.log

The reason for this is because of the bug in the "mysql_install_db.sh" script here: https://github.com/MariaDB/server/blob/374783c3d9a87170b313a05240dadaa813ec6034/scripts/mysql_install_db.sh#L379

Bug consists of two issues:
1. auth_pam.so might not exist unless mariadb-pam package is installed
2. "$basedir/lib*/mariadb/plugin" is missing in the list of directories

This results in plugin-dir set to empty string "" which causes the error that /usr/provider_lz4.so is not found.

I can create a pull request to fix this, but I guess it will be faster for core devs to do it?