After backporting #1870 (closed) to 9.11-S I saw that the condition check there is different than in the main branch. In 9.11-S "stale" can mean stale and serve-stale, or not active (awaiting cleanup). In 9.16 and later versions, "stale" is stale and serve-stale, and "ancient" means not active (awaiting cleanup). An "ancient" RRset is one that is not active (TTL expired) and is not eligble for serve-stale.
Update the condition for rndc dumpdb -expired to closer match what is in 9.11-S.
(cherry picked from commit 5614454c)
Closes #1870 (closed)