In this case error_count can be decreased before checking it for
rescheduling send.
And actually this can be a problem not only when
distributed_directory_monitor_{max_,}sleep_time_ms > 5min, because all
threads can be occupated and the real timeout between sends will be > 5min.
Since in this case it will be scheduled from the
DistributedBlockOutputStream with the
distributed_directory_monitor_max_sleep_time_ms, and this will overwrite
timer that was set by the DistributedBlockOutputStream, not good.
Before this patch each INSERT query re-schedule distributed send, thus
each time it resets the timer, while this is not the expected behaviour,
since in on frequent INSERT distributed sends will not be triggered at
all.
Fix this by not resetting the timer.
After #8756 the problem with 1 thread for each (distributed table, disk)
for distributed sends became even worse (since there can be multiple
disks), so use predefined thread pool for this tasks, that can be
controlled with background_distributed_schedule_pool_size knob.
