qapi: Improve documentation around job state @concluded

qapi: Improve documentation around job state @concluded

We use "the query list" in a few places.  It's not entirely obvious
what that means.  It's actually the output of query-jobs or
query-block-jobs.

Documentation of @auto-dismiss talks about the job disappearing from
the query list when it reaches state @concluded.  This is less than
precise.  The job doesn't merely disappear from the query list, it
disappears, period.

Documentation of JobStatus @concluded explains "the job will remain in
the query list until it is dismissed".  Again less than precise.  It
remains in state @concluded until dismissed.

Rephrase without use of "the query list" for clarity and precision.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20250527073916.1243024-14-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>