Manages the security risk in way that also fixes Lintian warning:
  W: mariadb-server-10.5: setuid-binary
  usr/lib/mysql/plugin/auth_pam_tool_dir/auth_pam_tool 4755 root/root

Applied downstream in
https://salsa.debian.org/mariadb-team/mariadb-10.4/-/commit/9605a48a99a61f439698676da192799de45d732a