Fix GCC warning about moving from a const reference in mp_row_consumer_k_l::flush_if_needed.
Since position_in_partition::key() returns a const reference, std::move has no effect.
Considered adding an rvalue reference overload (clustering_key_prefix&& key() &&) but
since the "me" sstable format is mandatory since 63b266e9, this approach offers no benefit.
This change simply removes the redundant std::move() call to silence the warning and
improve code clarity.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#23085
a3ac7c3d33