This bridge doesn't support SQLite anyway, so it's not necessary
to carry around configuration fields and code for migration from SQLite
to Postgres. There's nothing to migrate.
This configuration is supposed to be kept clean and not reference variables defined in other roles.
`group_vars/matrix_servers` redefines these to hook our various roles together.
Slavi Pantaleev
Aine
3hhh
Marko Weltzer
GoliathLabs
Alexandar Mechev