refactor($parse): don't use bind-once interceptor for non-bind-once expressions

Side-effects:
  - Logic for allOrNothing watches now lives in $interpolate rather than $parse

Credit to @jbedard for idea to remove $watch interceptors craziness from $interpolate. Even though
it technically didn't actually work, it was worth a shot, and helped clean things up a bit. Go team!

Closes #9958
Closes #9961