Reduce code duplication by replacing a code snippet repeated throughout
system tests using "trusted-keys" and/or "managed-keys" configuration
sections with calls to keyfile_to_{managed,trusted}_keys() helper
functions.
- all tests with "recursion yes" now also specify "dnssec-validation yes",
and all tests with "recursion no" also specify "dnssec-validation no".
this must be maintained in all new tests, or else validation will fail
when we use local root zones for testing.
- clean.sh has been modified where necessary to remove managed-keys.bind
and viewname.mkeys files.
