issue, no mariadb-server in provides
MDEV-7233: Fix issue with missing dependency socat
           when installing MariaDB-galera-server on
           RedhatEL/OracleEL/(Others?) RPM based 

* Added mariadb-server to "provides" for MariaDB Galera
  server package. (rpm)
* Removed "socat" from MariaDB Galera server's mandatory
  dependency list. (rpm)
* Moved "socat" from mandatory to optional dependency. (deb)