975cd60e05
After stop() moved _reaper, in-flight with_connection() callbacks could still call reap(), which accessed the moved-from future causing a SIGSEGV in future_base::detach_promise(). Add a seastar::gate so stop() waits for all in-flight operations before moving _reaper. Fixes https://scylladb.atlassian.net/browse/SCYLLADB-1043 Closes scylladb/scylladb#29015