Every push is marking all tracked users as dirty, thus triggering a `keys/query` for all users

It appears that everytime a push notification is received, a new notification client is created and will then do a sync without `pos`. This will trigger a `keys/query` for all tracked users.

This is apparently due to this change #3965
> fix(sdk): Mark tracked users as dirty when the SS connection is reset.

Here is the classical sequence of request as captured by a proxy:

Start by reviewing change #3965 and the captured request sequence. Trace notification client creation and the sync performed without `pos`; done when receiving a push no longer causes `keys/query` requests for all tracked users.

Written by the indexing model from the issue text.