For all system tests utilizing named instances, call clean.sh from each
test's setup.sh script in a consistent way to make sure running the same
system test multiple times using run.sh does not trigger false positives
caused by stale files created by previous runs.
Ideally we would just call clean.sh from run.sh, but that would break
some quirky system tests like "rpz" or "rpzrecurse" and being consistent
for the time being does not hurt.
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.
