Fix issues with INSERT and distributed sends in ClickHouse

Fixes: #10263 (after that PR dist send via INSERT had been postponing on each INSERT) Fixes: #8756 (that PR breaks distributed sends with all of the following conditions met (unlikely setup for now I guess): internal_replication == false, multiple local shards (activates the hardlinking code) and distributed_storage_policy (makes link(2) fails on EXDEV)). #10486 (Azat Khuzhin).