Detach rpzs and catzs from the previous view

Detach rpzs and catzs from the previous view

When switching to a new view during a reconfiguration (or reverting
to the old view), detach the 'rpzs' and 'catzs' from the previuos view.

The 'catzs' case was earlier solved slightly differently, by detaching
from the new view when reverting to the old view, but we can not solve
this the same way for 'rpzs', because now in BIND 9.19 and BIND 9.18
a dns_rpz_shutdown_rpzs() call was added in view's destroy() function
before detaching the 'rpzs', so we can not leave the 'rpzs' attached to
the previous view and let it be shut down when we intend to continue
using it with the new view.

Instead, "re-fix" the issue for the 'catzs' pointer the same way as
for 'rpzs' for consistency, and also because a similar shutdown call
is likely to be implemented for 'catzs' in the near future.