Streaming ususally takes long time to complete. Abort it on false
positive idle detection can be very wasteful.
Increase the abort timeout from 10 minutes to a very large timeout, 300
minutes. The real idle session will be aborted eventually if other
mechanisms, e.g., streaming manager has gossip callback for on_remove
and on_restart event to abort, do not abort the session.
Fixes#2197
Message-Id: <57f81bfebfdc6f42164de5a84733097c001b394e.1494552921.git.asias@scylladb.com>