squash with previous spec changes
Maint: Don't load facts twice during specs

Previously, the spec_helper was prepending facter's lib directory to the
$LOAD_PATH, which had the side-effect of causing the zfs and zpool commands
to be executed 5 times, not 3 (as specified in the comments).

Originally, this was noticed because we were having to add `.at_least_once`
to expectations even though the method should have only been called once.

This commit no longer prepends facter's top-level lib directory to the
LOAD_PATH. In doing so, it causes the virtual fact resolutions to be
evaluated in a different order than the virtual tests expected. In
particular, the tests we're trying to verify the more-specific tests, but
were trying to evaluate the more generic virtual facts first.

This commit adds a higher weight to the more specific virtual facts, since
that's the expected behavior, and it ensures the tests reliably test the
resolution they trying to set expectations on.