column_family.cc: remove unhandle future
column_family.cc: remove unhandle future

The sum_ratio struct is a helper struct that is used when calculating
ratio over multiple shards.

Originally it was created thinking that it may need to use future, in
practice it was never used and the future was ignore.

This patch remove the future from the implementation and reduce an
unhandle future warning from the compilation.

Signed-off-by: Amnon Heiman <ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@scylladb.com>

scylladb/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,avikivity/scylla,avikivity/scylla,scylladb/scylla