storage_proxy: metrics should have unique name
storage_proxy: metrics should have unique name

Metrics should have their unique name. This patch changes
throttled_writes of the queu lenght to current_throttled_writes.

Without it, metrics will be reported twice under the same name, which
may cause errors in the prometheus server.

This could be related to scylladb/seastar#250

Fixes #2163.

Signed-off-by: Amnon Heiman <ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@scylladb.com>
Message-Id: <20170314081456.6392-1-ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@scylladb.com>

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