I suspect the answer may be type dependent, but for the CRJs, the stab retrims when the AP servo sees a load above a threshold, so the design purpose of the trim motion is to relieve AP servo load while the AP is engaged.
This means that when the AP is disengaged, the aircraft will be close to in-trim - but by no means fully in-trim - but this is merely a useful side-effect of the operation, not its intent.
The only stab motion when the AP is disengaged is either pilot commanded (hardly auto-trim) or is a consequence of configuration or Mach number changes, and is not particularly intended to relieve forces, but rather to provide the desired force feel characteristics to the pilot.
So for those aircraft, the true answer is "neither", but the second is closer to the behaviour than the first option.