[v9_16] Fix catalog zone reconfiguration crash
The following scenario triggers a "named" crash:
- Configure a catalog zone.
- Start "named".
- Comment out the "catalog-zone" clause.
- Run
rndc reconfig
. - Uncomment the "catalog-zone" clause.
- Run
rndc reconfig
again.
Implement the required cleanup of the in-memory catalog zone during
the first rndc reconfig
, so that the second rndc reconfig
could
find it in an expected state.
(cherry picked from commit 43ac2cd2)
Closes #1608 (closed)