Allow preemption for non auto journaling

[adiholden]

Today non auto journal is recoded inside command callbacks and preemption is not allowed.
This reduces the backpressure from master to replicate this commands.
f.e if we run memtier with MSET, because MSET is non auto journal the journal changes are acumulated in master resulting in increase in memory usage and big lag

To allow preemption in callbacks we need to first make sure we dont have any assumptions in code that logic relay on the fact that callbacks do not preemt f.e OnCbFinish in db slice