Add `DeleteUsersInvitation` function to invitations repo to bulk delete invitations

We can have repo call where we can delete All the Invitation at once something like 

```go 
svc.repo.DeleteUsersInvitation(ctx,entityID, memberIDs...)
```

This requires new function invitations repo like ```DeleteUsersInvitation(ctx,entityID, memberIDs...)```

_Originally posted by @arvindh123 in https://github.com/absmach/supermq/pull/2835#discussion_r2128893065_
            