Change 8f39547d89 added
`handle_exception_type([] (const semaphore_aborted& e) {})`,
but it turned out that `named_semaphore_aborted` isn't
derived from `semaphore_aborted`, but rather from
`abort_requested_exception` so handle the base exception
instead.
Fixes#10666
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Closes#10881