[9.20] fix: dev: fix configuration bugs involving global defaults

The configuration code for the `max-cache-size`, `dnssec-validation`, and `response-padding` options were unnecessarily complicated, and in the case of `max-cache-size`, buggy. These have been fixed. The `optionmaps` variable in `configure_view()` is no longer needed and has been removed.

Backport of MR !11165

Merge branch 'backport-each-cleanup-defaultconfig-9.20' into 'bind-9.20'

See merge request isc-projects/bind9!11172