[Frozen Architecture] Consider automatic cleanup of intermittent versions

[cmelchior]

We only sweep the list of intermittent versions (RealmReferences) when the Realm is updated. This means that we might be holding on to memory longer than needed.

We should consider if it is worth implementing a background cleaner that cleans up the list at regular intervals.

Low priority.

[sync-by-unito]

➤ Christan Melchior commented:

Will be closed by #598

[rorbech]

➤ Christan Melchior commented:

Will be closed by #598

Updating the user face realm's intermittent versions on the realm_on_realm_change_func_t won't fix this issue. The clean up is still not performed until we iterate the weak references and this is still not automatically detecting when realm references/version are not used anymore. Reacting to the correct realm_on_realm_change_func_t will of course trigger the clean up more often, but it could still make sense to trigger periodically.