Fixup clean-all, clean-all-async and invalidate dependencies.

In the wake of Goal.dependencies no longer being used for scheduling,
clean-all and invalidate no longer properly depend on ng-killall.

https://rbcommons.com/s/twitter/r/638/
Technically clean-all doesn't need to depend on invalidate because its own action (nuking all of .pants.d) subsumes that of invalidate (nuking just the build cache). But I guess this is semantically correct, regardless of the implementation redundancy, so probably a good idea.