ktest: Have all values be set by defaults

Currently the patchcheck, bisect, and config_bisect variables
are only able to be set per test. You can not set a default
value for them.

By letting default values be set, it makes some config files
a bit easier, and also makes it easier to find typos in the
option names.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>