test-daemon: cleanup after removal of XbDatabaseCache

These operations are not needed anymore since the cache does not exist.
database-manager: remove query_all() API

It's unused.
database-manager: remove query_lang() API

It's unused.
Remove XbPrefixStore

It's unused now.
database-manager: remove remove_db() API

It's unused.
database-manager: remove has_db() API

It's unused.
database-manager: assert create_db_internal() operates on new paths
database-manager: invalidate database payload on file changes

Install a GFileMonitor to invalidate the database payload when an
application is updated or removed.