GraphQL replication: should stop syncing if we receive less docs than pull.batchSize

[jwallet]

This PR contains:

• IMPROVED TESTS (fail test)

Describe the problem you have without this PR

If we send the initialSync with a batchSize of 5, the server last response will contain less than the batchSize (let say 2) and instead of finishing the initial replication, rxdb will always request a last time because it ends only if there are no document in the response. Actually the batchSize interface tells us, that the replication will stops if the response contains less documents than the batchSize, which is currently not true

It will also be preferrable to resolve this case, cause we also prevent relying on the server to stop the sync process.
Currently we have, at work, a endpoint that need to be fix, it includes in the response the document that fits the checkpoint.updatedAt, so the initialSync() never stop.

• Tests

[jwallet]

sorry I'm not familiar with karma, I didn't find the equivalent of jest.fn() and expect().toHaveBeenCalledTimes(2). so I used a goold old count++

[pubkey]

Can you set live: false and check if that also fails?
This would ensure that no time dependend other sync-cycle is running.

[pubkey]

Fixed here #4116

[jwallet]

thanks @pubkey