'Consumer function' parameter for distribute_reader_and_consume_on_shards()
captures schema_ptr (which is a seastar::shared_ptr), but the function
is later copied on another shard at which point schema_ptr is also copied
and its counter is incremented by the wrong shard. The capture is not
even used, so lets just drop it.
Fixes#3838
Message-Id: <20181011075500.GN14449@scylladb.com>
(cherry picked from commit ceb361544a)