io_queue: Remove timestamp from queued request
io_queue: Remove timestamp from queued request

There's a timestamp mark on the owned desc object that's only used
after the request is dispatched. It's possible to reuse for queueing
timestamp and simplify the desc api.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>

scylladb/seastar,scylladb/seastar,avikivity/seastar,scylladb/seastar,syuu1228/seastar,syuu1228/seastar,avikivity/seastar,avikivity/seastar,syuu1228/seastar