Ensure that multiple `-k` completions intermixed with one or more non-`-k`
completions are produced in the expected order with the order of all completions
in a single `-k` completion respected, non-`-k` completions correctly sorted and
interspersed, and the results of multiple `-k` completions in the
reverse-intuitive order (with chronologically later completions coming before
chronologically earlier `-k` counterparts), as per #9221.
